G o A GENERAL COLLECTION
‘
OF THE G
BEST AND MOST INTERESTING
VOYAGES AND TRAVELS, |
IN ALL PARTS OF THE WORLD;
te
os
—< nininstientampanien as 2 Me
MANY OF WHICH ARE NOW FIRST TRANSLATED INTO ENGLISH. DIGESTED ON A NEW PLAN.
_——E— BY JOHN PINKERTON, AUTHOR OF MODERN GEOGRAPHY, &c.
EATER WEL EE ED
VOLUME FIFTH.
PUBLISHED BY KIMBER AND CONRAD, No. 93, MARKET STREET
William Falconer, New York ; Samuel Jefferis, Baltimore ; James Kennedy, sen. Alexandria ; Fitzwhylsonn a
« and Potter, Richmond; John Hoff, Charleston, South Carolina; Henry Cushing, Providence, R. I. ; John ay _ West and Co. Boston; Cushing and Appleton, Salem; Edward Little and Co. Newburyport; Charles, ah Tappan, Portsmouth. ms
ge "~ PHILADELPHIA:
‘
MERRITT, PRINTER, WATKIN’S ALLEY. " i
1812.
Nt : ie eee a gees fait. Sate aaa ave aE emnemmanentesA ht= Ss we eas
By tranefe:
tAAY 17 1916
aie
CONTENTS
OF THE
FIFTH VOLUME.
es Page. SPALLANZANI’S Travels in Italy, Pa hie a ae 1 Dolomieu’s Account of the Earthquakes in Colabriain 1783, - -° -° 278 Bourgoanne’s Travels in Spain, - °°. °° ae . . - 298 Cowe’s Travels in Switzerland, * =" " "7 * * - + 640 ¢” & oe
LIST OF PLATES IN VOLUME V.
Page _ t. ETNA, from Catania, — - . ° ° ° ° 6 : : 6l * 2, Summit of Etna, : . : ° ° ° " P ‘ 17 ' 3. Etna, from the East, ° ° . ° w ° a a - 89 ' 4, Spanish Inn, “ - . ° eee ° ° ‘ 302 5. Castle of Segovia, . : : - ° ° ° ‘ ‘ 322 G. Fandango, : . . . . . ° ° ‘ . 517 7. The Devil’s Bridge, . . . - ° ° ° ° , 745 » 8. Source of the Rhone, — - - . - . . : ° é 750 9. Lake of Kandel Steig, - ~~ - ° ae Hig . s 164
» 10. Saussure’s Ascent of Mont Blanc, - . ° m « . Z 788 — 11. The Alps, as seen from Berne, : - : . . . ° 873 12, Mount Rosa, —- zs - + + «+ Atthe End of the Volume.
, 13. Source of the Arveron,
\
OF
@ES AND TRAVELS.
ot (TRAVELS
ie +,
Mh ae Raat ag
IN THE
mae
‘ D WR (ira ORIGINAL ITALIAN OF THE ‘ABBE LAZZARO SPALLANZANI, Professor-Royal of Na ee ‘the niversity ‘of Pavia, and Superintendant of the Imperial Museum in that city JRellow of the Royal Society of London; and Member of the Academies of Prussia, Stockholm, Gigttingen, Tut 4
' BY THE TRANSLATOR.
'
THE name afi eamab
on.of the abbe Spallanzani must certainly be a sufficient recommiee
p. work he gives to the public, especially of one like the present, on whim Dpears to have: bestowed a more than ordinary degree of la- bour and attention. Heat B Variety of objects; highly interesting to the naturalist and the philosopher, on w Ni at treats, mn ye acen in the following introduction, which con- tains, in part, a sun} Me ee
In the translation\ it is presumed, has! may be allowed) itt! translator thought give his idea with ¢& will frequently ren¢ #3 in every work, espe sionally be found) + that the reader may! 4
original, eR * T he parts least interesting to the general reader are omitted. B
ive been principally studied. The reader, 1 me 4 of the original (if the expression
sy Where the meaning admitted of no doubt, the @epart from the phraseology of his author, to hich the different idioms of language lhadow of ambiguity appe (and ambiguities of expression will occa- adh fo.'the literal expression of his text, Rihis nent in the same manner as from the
VOL. Vv.
2 SPALLANZANI’S TRAVELS
As the abbe has continually employed the terms of what is called the new nomen- clature of chemistry, it has been thought proper, for the benefit of readers not familiar with this science, to add, in a parenthesis, the more usval names of clemical substan. ces; a for instance, to subjoin to muriate of alumine the common term of alum; and to rauriate of soda that of sea-salt. The abbe has likewise used the term caloric, on all occasions, instead of heat or warmth. In this the translator has npt judged it advisable to ny him, except when he has employed it in the proper chemical sense of the mat- ter of heat.
The igs are faithful copies of those in the original, but more finished. Some may, perhaps, object to the disproportionate siz represented in plates II, III, and V. This objection the author end of vol. IV, apologizes, by remarking, that “‘the painter
rmitted this licence, as, had he attempted to ovserve the ru
gures would have been scarcely discernible.”*
The work in the original is dedicated to count Wilzeck, im the general administration of Austrian Lombardy ; but as this dedi the eulogiums of which such compositions ously consist, it has
refully and elegant! of the human aa
foreseen, and, at the reived he might be ‘ of proportion, these
omitted.
} i INTRODUCTION. ial
i THE zeal with which I have always been animated to contributejas much as might be in my power, to the improvement of the Public Imperial Musuem of Natural His- tory in the University of Pavia, by enriching it with the new and imgyrtant productions I procured in the various journeys and voyages I undertook bothjn Italy and other countries, incited me to travel, during the summer and autumn vacapns, into the Two Sicilies. Though this Museum abounded in other kinds of natyal productions, it was extremely deficient in volcanic matters, which merely consist,'l of a few trivial scorie of Vesuvius, and some extremely common lavas of the sag: mountain, that, having been cut into tablets and polished, had lost their distinguig$ng characteristics, and consequently could little contribute to the instruction of youg. and the advance. ment of hhowied As I knew that no countries in Europe could furnish a more am lection of volcanic products than the Phlegrean Fields, Mount E Lipari Isles; I resolved to visit them, and employed several months. ful researches. ‘To make a proper choice, however, of the subst@zes suitable to the design I had in view, it was necessary to examine on the spot thefirious qualities of the bodies composing those volcanized regions, ‘This I: performedivith the same dili- gence and care I have usually exerted in the examination of other‘nghral objects. Still more to enable myself to make this selection, and correetimy. judgmgnt with respect to these subjects, I had read, and then re-perused, whatever, and the most eminent naturalists relative to volcanos, and ‘was sincera grateful to them for the instruction I derived from their works. “In the course Of. thiginquiry, however, I discovered what I had often experienced before, with respectto othe subjects, in which Thad been preceded by other naturalists, that, notwi ing the’elegnt and interesting accounts they had given us of the countries which have 'siifferedithe agion of fire, it was
see Meat cine t
5 °
: and valuable col- a, and Eolian, or laborious but use-
aC mn iGritten by travellers ei AR ‘
* These plates are omitted as a disgrace to the state of the arts in the eighfler
h century. Tho view of the crater of Etna is that of a well!
IN THE TWO SICILIES, §
still possible to add to them by my researches, and throw new light on volcanic know- ledge. This I say not to arrogate to sayself any merit, and still less to detract from that of others. ‘The powers of the human mind are so limited, that it never can entirely ex- haust the subject it investigates, Other naturalists who shall hereafter diligently explore the countries through which I travelled, it is not to be doubted, may improve this part of natural history with still new discoveries. In like manner, though others have written of the Phiegrean Fields, Etna, and the Eolian Isles, the observations I have made appear to me to merit publication.
The method in which I prosecuted my researches in these Travels was the following : I have endeavoured to study volcanic countries as mountains should be studied. The lithologist who would acquire an accurate knowledge of the latter, attentively considers their structure of rock, the whole of their huge masses, the position and direction of the various parts or strata which compose them, and the intertexture and relations of those strata. I have adopted the same mode of inquiry in the course of these travels. Fire in conjunction with elastic gases has formed whole mountains and islands ; but all of them have not been produced in the same manner, nor are they composed of the same substance. Here we find large masses of tufa; there of scoriz and lavas; in an- other part, pumices, enamels, and glasses; and in another, a mixture of all these sub- stances. It was therefore necessary to examine them on the spot, and observe, both when they were separate and intermingled, their relations, directions, mixtures, &c. without once losing sight of the peculiar composition of these volcanic mountains, every part and recess of which it was requisite I should explore.
In these inquiries I particularly directed my notice to two objects; the central sum- mit of the islands and mountains, and their shores. The former is usually the first sensible effect of the subterranean conflagrations, the part which first emerges from the waves, which often preserves the crater entire, and sometimes burning, but more fre- quently only its recognizable traces. The shores of volcanic islands and mountains bathed by the sea, were also peculiarly entitled to attention, nor do I know that any volcanist who has hitherto travelled has made them one of the objects of his inquiry. We know how much it conduces to an accurate knowledge of the structure of moun- tains, to cross, or go round them in the beds of torrents which have corroded their foundations, and laid bare a part of their sides ; thus revealing, if I may use the ex-
ression, their internal organization, which without this aid would have been sought in vain drom external ap ces. ‘The sea, by incessantly beating with its furious wayes the skirts of the has caused fractures and ravages incomparably greater than those occasioned by rivers. By coasting, therefore, these shores in a boat, land- ing where they appear to invite parolee attention, and examining their open sides, and rocks half fallen down and falling, we may observe a variety of important facts conducive to the improvement of that kind of science. I shall not here enlarge on the a to bederived from coasting volcanic islands ; in the course of this work they. will be provéd by: facts.
The researches.I made in.volcanic’countries, though necessary, and highly instructive were not, however, sufficientto. complete my. design. As lithologists are not satisfied
-with knowing. the:structure, ; stratification, and other general qualities of mountains, - butendeavour likewise to.discover the nature of their component parts, I resolved not
to depart from the. same method:of inquiry. It is true that some volcanic. produc- tions are so altered by. the fire, that it is difficult to ascertain the nature of the earths from which they:have been produced, unless we callin aid the processes of chemistry. Such are enamels, glasses, and frequently — But lavas, which,:in the greater :
4 SPALLANZANI'S TRAVELS
part of the places where I made my observations, are abundant beyond all belief, are — so changed by the fire as not to retain the evident characters of their primitive rocks,
I began, then, by considering the external appearance and qualities of the places I ex- amined, as far, at least, as circumstances would permit.
Whoever has undertaken to travel among mountains, in order to make researches relative to the fossil kingdom, is not ignorant to what changes the surfaces of stony substances, even the most solid and hard, are subject, from the action of the clements during a long series of years and ages, Hence, if he would form an accurate judg- ment of the stones he examines, he will not fix his attention on those found on the surface of the earth, but rather on those buried at some depth, and will frequently forcibly .reak and detach them from the internal masses of which they are a continua. tion, Still greater changes take place in some parts of the mountains which throw out fire, from the action of sulphureous acid vapours, besides that of the atmosphere and of time; and very frequently the volcanic ag og which on the surface seems to be of one kind, and at some depth, of another, is in fact the same, but more or less changed in the first instance by the action of the atmosphere, or that of sulphureous vapours.
To render my researches more accurate and certain, it was necessary that I should not content myself v th a single inspection of the volcanic substances, on the spot where I gathered them. I therefore, when I returned to Pavia, re-examined them with the
atest care, in the retirement of my study; not only with the naked eye, but with the aid of the lens, before I began to characterise and describe them lithologically. ‘The reader will find some of the descriptions rather diffuse ; and, perhaps, I may be charged with having been too minute. But it appeared to me that I could not be more concise ; us a detailed description of such procincts can alone enable us to discover to what kind of rocks they appertain, and what is the particular characteristic of the volcanic coun- tries in which they are found. ‘Those who, when treating of volcanos, have been sparing of such desc.iptions, have left us imperfect works, though in other respects they may be very valuable. All who are versed in these subjects, are acquainted with the ac- count of the famous eruption of Etna in 1669, and the memoirs relative to different remarkable conflagrations of Vesuvius by Serao, Della Torre, Sir William Hamilton, and Bottis. With tespect to what regards the currents of lava which those two vol- canos at those times poured forth, the symptoms and phenomena that accompanied them, and the other circumstances desesving notice which preceded and followed them, their histories certainly merit great commendation, They will be highly valuable in the estimation of every lover of volcanic science; and I have frequently, in the course of this work, derived such assistance from them as demands my grateful acknowledg- ment. But from these relations, what idea can we in general form of the nature of the products ejected, and the currents they have formed? When do they describe with sufficient accuracy a single substance ? Aftcr having read these relations of the violent eruptions which have burst from the sides of Vesuvius and Etna, we femain profoundly ignorant, to what primitive rocks they appertain. I mean not by these remarks to in- jure the reputation these writers have justly acquired. Their deficiency in lithological studies, not cultivated at that time as in the present, is a sufficient excuse ; I intend only to shew the necessity there is for circumstantial description, which, in fact, form the basis of all solid science.
It is necessary that I should here mention, with respect to the descriptions I have
iven of the different products of the various volcanic places I visited, though *
ve treated diffusely, and in detail, of those of the Phliegrean Fields, situated to ‘i:
ef, are mitive
s I ex-
arches ’ stony »ments
judg. on the juently ntinui- ow out and of o be of hanged urs. wuld not where I ith the ut with y. The charged ONCISE ; at kind ¢ coun. sparing ey may the ac- ifferent amilton, wo uber
nie aha able in course owledg- ature of violent foundly s to ae ol ica sabscily basis
I have ough ¢ od to ‘che
IN THE TWO SICILIES. 5
west of Naples, and of others of the Eolian or Lipari Isles ; I have only spoken inciden.- tally of the productions of Vesuvius and Etna, though both these volcanos have furnished me with a great number of specimens for the Museum «t Pavia; not only because that to have examined these two mountains minutely, would have required years instead of a few months; but because a rape ag, of these has already been executed with givat ability by the Chevalier Gioeni, in his Lithologia Vesuviana, and by M. Dolomieu, in his * Descriptive Catalogue of the Products of Etna.”
The opportunity afforded me by having these volcanic substances continually under my inspection at Pavia, induced me to make new experirients on them. It is certain, that the greater part of them contain iron, Yet the proof of this by experiment was not superfluous, as the greatcr or less quantity of the martial principle might thus be dlis- covered, I therefore used, according to circumstances, the magnetic needle, or mag- netized knife. I applied the former to the products reduced to powder, and the latter to those in fragments ; taking care that they should always be,~as far as I was able to effect it, of the same configuration and volume. I then observed the different distances at which they attracted the magnetic needle, witnout noticing the pieces which exerted no such power, though I do not mean by that to deny that they contained iron.*
I was attentive at the same time to an inquiry of much greater importance. Vesu- vius, Etna, the Eolian Isles, and Ischia, are large mountains formed of rocks which have undergone liquefaction, and sometimes a true vitrification ; such has been the vio. lence of the subterranean conflagrations., What fire can we produce equivalent to these effects ? I have discovered that the fire of the glass-furnace will completely fuse again the vitrifications, enamels, pumices, scorig, and lavas of these and other volcanic coun. tries. The same will, in like manner, vitrify rocks congenerous to those from which these mountains have originated by the means of subterranean conflagrations, A less intense fire, on the contrary, produces no such effect on any of these sulstances.
As I wished to attain to the most rigorous accuracy in this experiment, I was not sa- tisfied with discovering that the fire of the glass furnace was capable of effecting these fusions; I determined, if possible, to ascertain the precise degree of heat necessary to
reduce them, for which purpose nothing could be hetter adapted than the pyrometer of edgwood. ‘This instrument, it is well known, is composed of two parts: the thermo- metric picces and the gage. ‘The fortocr are small cylinders of very fine clay. ‘The latter, which is six inches long, is formed by two pieces of the same earth, the internal sides of which are straight and smooth ; but so disposed as to be more distant irom each other at one extremity than the other, thus forming a converging space divided into two hundred and forty parts. ‘I'he greater aperture of this gage is the beginning of the scale, and denotes the heat which produces a beginning of redness in iron. If, there. fore, one of the clay cylinders shall have been exposed to a greater heat, it will be con. tracted, and sink lower between the converging sides; and, the sides being graduated, the degree at which it stops will be the measure of its contraction, and consequently of the degree of heat it has undergone ; the cylinders, as the inventor has observed, re- presenting the mercury, and the converging sides the scale of the thermometer.
To ascertain, therefore, the degree. of Plesk in the glass furnace necessary for the fusio of these volcanic productions, and the rocks whence they derive their origin, I made use of this pyrometer in the following manner. I placed in the furnace, near the sub. stances I intended to fuse, one or more of the clay oylinders above-mentioned, in a case of
* As the iron is sometimes in the state of oxyde (calx) Iemployed the usual methods to revive it in the productions I examined. thai ii ‘
te
; y 6 SPALLANZANI’S TRAVELS
the same clay, and let them remain there the whole time necessary for the fusion of those substances. I then measured their contraction by the gage; and found that the heat of the glass furnace was 87} degrees of this pyrometer; a heat, according to the observa- tion of the inventor, but 2} degrees less than that of welding iron, which latter heat corresponds to 12,777° of Fahrenheit’s thermometer.* — In fact, filings of iron (in which the surface of the metal is greatly enlarged) being continued four-and-twenty hours in the glass furnace of Pavia, of which I always made use in these experiments, congluti- nated into a solid though friable body, and shewed an evident beginning fusion. Whence 1 conclude that a greater heat is usually kept up in these furnaces than is necessary for the fusion of glass.
Though the blowing pipe did not in general greatly conduce to the success of my ex- periments, I sometimes found it useful. In some cases I likewise had recourse to the assistance of fire excited by oxygenous gas (dephlogisticated air. )
There is scarcely any natural product, volcanic or not volcanic, of which I have treated in this work, that I did not try in the fire, in one or other of the manners I have described, and frequently more than once. These experiments in the dry way I often accompanied with others in the humid, with respect to the productions of volcanic fire. ‘The manner in which I proceeded was as follows :
When the external appearance of these products perfectly agreed with that of earths not volcanic before known, and analised by able chemists ; 4 thought I might determine the genus of the volcanic production without analysing it in the humid way ; and when I made experiments on a few pieces, I found I was not deceived. _ But when the exter- nal appearance appeared to me new, and not to agree with that of the earths already known, I then had recourse to an examination by the humid method, by which I eluci- dated the genus, and frequently the species, of these substances. Before, therefore, I proceeded to describe any pieces I had collected, I was certain, or thought myself so, that I had obtained a sufficient knowledge of them. And when I could not arrive at this knowledge, but remained uncertain to what genus they appertained, I have never failed to express myself doubtfully. In these researches, equally laborious, delicate, and necessary, I have employed much of my time, not without considerable expence. In my volcanic travels I have been obliged to take upon myself the parts both of naturalist and chemist. ‘The natural history of fossils is so closely connected with modern che- inistr”, and the rapid and prodigious progress of the one so exactiy keeps pace with that of the other, that we cannot separate them without great injury to both. But as the chemist in his laboratory can reason but imperfectly concerning the mountains, the com- ponent earth of which he analyses; so the observations of the lithological traveller must always be defective when not conjoined (at least when it may be necessary) with chemical investigations. What is true of fossils not volcanic, must likewise be so, ina certain degree, and with necessary allowances, of volcanic fossils. Here, in fine, neither observation alone, nor experience alone, are sufficient ; but both must join to conduct the investigator of nature, or he cannot be successful in his researches.
Where my experimeniz! inquiries have been short, I have incorporated them with my narrative ; as they are relative to the productions I met with in the different places I visited. But more than once I have found it convenient to act otherwise; and the sub- jects treated, appear to me to justify the method I have adopted.
What is the activity, in general, of volcanic fires, has been a question long agitated, and which is certainly of difficult solution. In this dispute, writers have gone into op- posite extremes ; some asserting that these fires are extremely active, and others that they
* Journal de Rozier, tom. xxx.
IN THE TWO SICILIES. 7q
are very feeble, while all endeavour to support their opinions by facts. Having treated on volcanos so much at length in this work, I could not avoid considering this question. I have weighed the arguments on both sides without prejudice ; I have made various experiments ; and declared in favour of the opinion which appeared to me to have the strongest support from reason and from facts.
The nature of elastic gases by which the liquefied matters of volcanos are penetrated and agitated, was another subject well deserving attentive consideration. ‘The vacuities, inflations, and tumors, which such matters frequently retain in a state of congelation, can only be ascribed to the elasticity of these gases while they were in a state of liquidity. Our common fire will reproduce in them these gases equally with the volcanic. In fact, many lavas, pumices, glasses, enamels, and scoriz, though by pulverisation they may be deprived of these vacuities, which are more or less large, and usually orbicular, re- cover them by refusion in the furnace; and in many of these bodies the gaseous bubbles are so abundant, that by their great inflation, while in actual fusion, they force them to flow over the edges of the crucible. ‘These observations led the way to inquiries rela. tive to the qualities of these gases, by liquefying in chemical furnaces volcanic substances reduced to powder, and placed in matrasses fitted to a chemical mercurial apparatus. By a great number of experiments of this kind I discovered the true nature of these gaseous substances, of which our knowledge was before very vague and uncertain.
This discovery naturally led to the inquiry what part the elastic gases take in the eruptions of volcanos; and this inquiry to a discussion of the causes of those cruptions.
The chemical processes I employed to ascertain the characters of the gases of volcanic productions likewise discovered to me a new fact, which was, that several of these pro- ductions contain muriatic acid. This discovery again produced new inquiries.*
Lastly, 1 must not omit the researches relative to the origin prismatic or basalti- form lavas. It isan opinion almost universal, that lavas take this regular figure in the sea, by the sudden condensation and congelation they suffered when they flowed into it in afluid state. I could not have met with examples of this kind more proper to enable me to form a judgment on the subject than those which presented themselves to my view ve coasting the shores of Italy, a great part of Etna, and the whole of the Lipari
slands.
These different discussions relative to the efficacy of subterraneous conflagrations, the gases of volcanic productions, the causes of the eruptions of volcanos, and the muriatic acid contained in various of their products; with the inquiries concerning the origin of basaltiform lavas ; to treat them at length, as they required, would have too much bro- ken the thread of the narrative of my travels. I have therefore placed them in such a manner as not to interfere with my accounts of the Phlegrean Fields, Etna, and the Eoliar Isles.
In the volcanized countries in which I travelled, there are four craters still burning, Vesuvius, Etna, Stromboli, and Vulcano. ‘To all these four, from an ardent desire of obtaining knowledge, I wished 10 make a near approach. By Vesuvius this wish was not gratified ; but Etna was more condescending, though incomparably more formida- ble ; and a similar good fortune attended me at Stromboli and Vulcano. The clear and distinct view I had of these three craters was equally pleasing and instructive. The crater of Etna I delineated myself; the views of Vulcano and Stromboli are the work of a draughtsman I took with me for that purpose, and who likewise furnished me with
* In these chemical experiments I was greatly assisted by the Signors Nocetti, father and son; the former operator in the public school of chemistry in Pavia, and the latter repeaterin the same. They are both well versed in chemical science, and are entitled to my grateful acknowledgments.
8 SPALLANZANI’S TRAVELS
drawings of some other volcanic mountains described in this work. I shall only add, that all these designs have been retouched and greatly improved by Sig. Francesco Lanfranchi, an eminent painter in the university of Pavia. .
The origin of the Lipari islands, which are the productions of fire, was certainly the principal motive of my visiting them; yet in many other respects they are certainly very interesting. The character, manners, and customs of the inhabitants; their po- pulation, agriculture, and commerce, are objects well deserving inquiry, and have the greater claim to the attention of an Italian, from their being so little known in Italy.
I have also made some observations on the animals in those islands, as for instance, on a kind of birds which with us are birds of passage, but there (in part at least) station- ary ; I mean swallows. Some years ago I made observations on the natural qualities of several species of swallows (the hirundo rustica, urbica, riparia, apus, melba, Linn.) and to these Inow add those I made in the Lipari islands,
The environs of Messina, where, after I had finished my volcanic travels, I remained more than amonth, afforded me much instruction, from the variety of natural objects they presented, ‘Though four years and a half had elapsed since that unfortunate city had been laid in ruins by earthquakes, the melancholy scene was still fresh in every one’s memory. <A great part of the public and private edifices were still in the same ruinous condition to which they were reduced by that calamitous event. Numbers of the inha- bitants still continued to lodge in the half-destroyed houses, and others in huts and sheds; while they all appeared oppressed and overwhelmed with fears from which they had not yet recovered. The impressions made on me by what I saw of the effects of this calamity were such that I could not refrain from giving a brief account of the me- lancholy situation in which I found Messina, and of the destruction occasioned by the dreadful earthquake in 1783.
Scylla and Charybdis, the former distant twelve miles from Messina, and the latter about a hundred paces within the famous Strait, were two objects to which I first turned my attention. That part of the sea being then calm, at least as calm as the Strait of
essina can be, I was enabled to take a-near view of them both, and even to pass over Charybdis ina boat. I also made inquiries of the Messinese sailors, who are employed the greater part of the year in that Strait, and consequently have an opportunity of form- ing a just and precise idea of these two celebrated places ; and from what they told me, and the observations I made myself, I am convinced that Charybdis is not a real whirl- pool, as has been hitherto believed.
In the Strait of Messina I found other instructive natural curiosities furnished by the fisheries for the sword-fish (Xiphias gladius, Linn.) the ravenous shark (Squalus carcha- rias) and for coral (Isis nobilis. )
Being at Messina at the time of the annual passage of the sword-fish through the Strait, I was present at the fishery, which appeared to merit some description, from the singular form of the vessels employed in it ; the method of striking and taking the fish ; and the qualities and periodical migrations of the animal. I have likewise made some observations on some fish of the genus of the squalus, particularly the shark, sometimes so dangerous to fishermen in that sea. } Coral, for which the Messinese mariners fish the whole year, by ayng with nets
en long an
suitable to the purpose from the rocks at the bottom of their Strait, has
_ ambiguous production, and made to pass through all the three kingdoms of nature ;
some considering it as a fossil, others as a vegetable; until at length it has been proved ye la to the class of animals, though it has the appearance of a plant; and is therefore now properly classed among the zoophyta. The excellent observations of
at Re Se et a CER OL tC TOR en meet eee
IN THE TWO SICILIES. 9
Peyssonel and Vitalianio Donati are well known; nor ought Marsigli to be denied the raise he merits, though a zealous maintainer that coral is a plant. Notwithstanding, however, these great discoveries, much was wanting to a complete history of this noble zoophyte, to which, I flatter myself, I have in some small degree contributed by the ob. servations I made on it at the time of the fishery, at which I was present. On this occasion, while the fishermen were throwing the net for the coral, I employed myself in researches for marine animalcuia. I carefully examined every picce of a stalk, leaf, or other fragment of a marine plant, or any thing else which hung to the net,
4 having learned from experience that these substances sometimes contain wonders in the ; class of animated beings; for, as Pliny has wisely remarked, nature is greatest in her | ) least productions. When the fishermen, therefore, turned up their nets to free them | from the weeds which were mixed with the coral, I put these weeds into glass vessels, 1 filled with sea water, to observe the animals adhering to them, and select those which | . appeared to present any remarkable novelty. Several of these were not wanting; of the genera of the ascidiz: and the eschare. - 1 likewise discovered some small polypi, in f which I could distinctly see the circulation of the fluids; which has not, to my know- " ledge, been before observed in these minute animals. The description I have given of | " them is accompanied with the necessary figures. d The surface likewise of the Strait of Messina was equally favourable to my researches y with the bottom. In other parts of the Mediterranean, the Adriatic, the Archipelago, of and the Strait of Constantinople, I had examined several species of those molusca which 9 are commonly called medusz. I had admired the simplicity of their organization, and ‘2 especially that property by which certain species of them, of the weight of twenty pounds | or more, dissolve almost entirely into a liquor, nothing remaining of them but somc ne thin and dry pellicles, which are only a few grains in weight. I had never, however, od met with any of that phosphorescent kind which Leeflingius tells us he saw in the ocean of between Spain and America. The mention he has thus made of them, without addin ee any further observations, can only serve to excite the curiosity of the reader; nor do ed know that any other author has described this rare animal. In the Strait of Messina I my had the pleasure to find abundance of these phosphorescent molusca, and the stay I e, made in that city afforded me an opportunity to examine their organization, their mo- rl. tion, and the beautiful light they emit in the dark. I concluded my researches relative to the natural objects in the vicinity of Messina, by he examining the shore, hills, and mountains, which on the side opposite the sea look ates toward that city. Icould discover no sign of volcanization ; but I observed, first, im- mense masses of testaceous and other animals petrified, the species of which were per- he fectly distinguishable. Secondly, granite, which probably is a continuation of that of he Melazzo, distant fromm Messina thirty miles to the north; and with respect to which I h; endeavoured to ascertain whether it formed strata, as some suppose, or only great masses, me as isthe opinion of others ; as also whether it contained within it petrified marine bo- | nes dies, as has been conjectured. Thirdly, sand stone, which, it appears to 1ne probable, forms, in a great measure, the bottom of the Strait of Messina, extending to the point ets Pelero, and being reproduced by a petrifying principle. We shall see that by means of an this principle, human skeletons, and other extraneous bodies, are sometimes found re; included in it; and that, in consequence of the same, at the part near Peloro, where ved the Strait is narrowest, it is probable that Sicily, losing the name of an island, will one 1 is day be again joined to Italy. ; of Having made the circuit of the Phlegrean Fields, the Eolian Isles, and Etna, the prin-
cipal objects of my travels, I returned a ia going by sea from Naples, with- VOL. v.
10 SPALLANZANI’S TRAVELS
out the least thought of making any new observations. But the lake of Orbitello, cele- brated for the immense quantities of large eels (Murena anguilla Linn.) it produces, became a new incentive to my curiosity ; and a dead calm detaining the veustl is which Thad taken my passage several days at Porto Ercole, a few miles distant from Orbitello ; as I could easily obtain as many eels as I chose, I examined them with great attention, to discover, if possible, the manner in which they propagate their species, since, not- withstanding the numerous experiments that have been made both by ancient and mo- dern naturalists to elucidate this question, it is not yet known with certainty whether they are viviparous or oviparous. ‘To the experiments I now made, when I returned in- to Lombardy, I added many others in the following years, made in every season.
With this view expressly I repaired to the lakes of Comacchio, which, with that above. mentioned, abound more with this fish than any in Europe. I here assiduously studied the various qualities of the animal, in order to illustrate its history, which is in many respects deficient and obscure.
The last place at which I landed before my arrival at Genoa, was the island of Elba, where I was obliged to remain five days in consequence of another calm. I profited by this delay to visit the ancient and celebrated iron mines, where I procured for the Imperial Museum at Pavia some noble specimens of that metal crystallized, and aug- mented the copious collection I carried with me with some sulphures of iron (pyrites. )
I returned to the university about the end of the year 1788, having employed six months in my travels in the two Sicilies ; with which, though they were at my own ex- pence, like the greater part of my other travels, I am well satisfied, since I have been able to contribute something to that noble public institution the Museum at Pavia; but my satisfaction will be still greater, if the work I now present to the public be approved by. its readers.
Thus I employed the summer and autumn vacations of that year. Some time before, but especially in the vacations of 1789 and 1790, I made researches among the moun- tains of Modena and Reggio, with respect to objects which, as they have a relation to volcanos, may have a place in this work.
The fires of Barigazzo, which burn on the Apennines of Modena, have been lone known. These consist of groups of feeble flames collected in a narrow space, which rise above the earth, are almost always visible, and, if by chance they become extinct, may be rekindled by bringing a small flame to the spot where they were. The accounts of them, however, are so few, and so defective, that at most they can only serve to compare the present state of these flames with what it once was. The light afforded by modern physics enables us to affirm, without farther. examination, that the cause of this feeble fire must be hydrogenous gas (or inflammable gas.) I made a journey to Barigazzo purposely to ascertain this, and found it to be the fact. In that vicinity there are six other similar fires, at present only known to the Alpine peasants, all originating from the same principle. :
But in the present accurate state of our knowledge relative to aeriform gases, itis too little to say and prove that the cause of these various flames is hydrogenous gas. The following are the principal inquiries which I think it necessary for me, as a naturalist, to make with respect to these fires, and such objects as may havea relation to them.
First, to examine the structure and composition of those mountains; and here I shall incidentally have occasion to speak of Cimone, not far distant from Barigazzo, and the highest mountain of our Apennines.
Secondly, carefully toremark the qualities of each of these fires, and the phenomena
- aecompanying them.
a seme ee ee I IE TTR TTT tee
IN THE TWO SICILIZS. il
Thirdly, to compare these fires nourished by natural hydrogenous gas, with those produced by hydrogenous gas procured by art.
Fourthly, to make a rigorous analysis of the hydrogenous gas of ihe fires of Barigaz. zoand the other neighbouring places, by means of the chemical mercurial apparatus , and to carry to those Alpine heights vessels to contain the different aeriform fluids, and instruments necessary for these analyses.
Fifthly, to make the same analysis of the earths from which these fires arise. And herc I must observe by the way, that having made at Barigazzo an excavation of some depth and size, in order to obtain the earth pure; the fires multiplied so much, and became so powerful, that, after I had left the place, the hollow was employed as a furnace for lime, and lime-stone as perfectly burnt in it as in furnaces prepared for the purpose.
Sixthly, toexamine what may be the matters generative of this inexhaustible supply of hydrogenous gas, which has been so long, continually developed ; it belag certain, from authentic documents, that these fires have burned for a century and a half.
In the hills of Modena and Reggio we find certain places which the people of: the country call Salse, and which area kind of volcanos in miniature, having the form ex- ternally of the truncated cone, and internally of the inverted funnel. ‘hey sometimes | throw up into the air earthy matters ;_ which at other times overflow, and, pouring down their sides, form small currents. After the manner of burning mountains, they fre- quently open with several mouths, and like them rage, thunder, and cause slight earth-
uakes around them. But in the true volcanos the primary agent is fire ; in these salse generative principle is entirely different,
Some of them have hitherto remained wholly unknown to naturalists ; of others au- thors have written, but have described the phenomena with little accuracy and frequent exaggeration; not to mention that, at the time when they wrote, the nature of the agent from which these phenomena derive their origin was not discovered.
_. These salse have claimed my attention equally with the fires above mentioned; and
Ihave applied myself to study them with equal assiduity, and with the same chemical
analysis; and as they both, after the manner of volcanos, undergo changes which appear
sometimes to have relation to those of the atmosphere, I have judged it necessary fre- quently to visit them, and in different seasons to observe the various phenomena, and. \ with more certainty discover the secret causes to which they owe their origin.
The Travels, 1 now present to the public, and of which I have here given the sum- mary, will be speedily followed by another work containing an account of my voyages to Constantinople, in the Mediterranean, and in the Adriatic,
63
CHAPTER I.
A VISIT TO VESUVIJUS DURING THE TIME OF AN ERUPTION.
TRAVELS, &c.
Little notice taken by the Neapolitans of the smaller eruptions of this volcano....Phenomena ob- served by the author on his arrival at Naples....His approach near to the crater prevented by showers of ignited stones, and acid-sulphureous fumes....E-xtraordinary phenomenon relative to these showers....Explication of gerd enomenon....Remarks on the congelation of a torrent of
lava....Observations on a stream of lava flowing within a cevern....Projected experiment for measuring the quantity of heat in the flowing lava....Other observations on t’.* lava issuing from a subterrancous cavity....Remarkable cataract formed by it in its passage....Length, breadth, and termination of this torrent.,..Phenomena of this eruption of Vesuvius compared with those of preceding ones....Erroneous opinion of some naturalists, that the lava is not fluid, but of the consistence of paste....Composition of this lava....Observations on a lava of Vesuvius which ‘flowed in 1785....Proofs that the shoerls and feltspars found in the lava existed previously in the primordial rocks. ) WHEN [I arrived at Naples, on the 24th of July 1788, though Vesuvius was not in
a state of inactivity, its conflagration was not sufficient to excite the curiosity of the Neapolitans ; who, from having it continually before’ their eyes, are seldom inclined to visit it, but during its great and destructive eruptions. At that time, during the day, it without intermission sent forth smoke, which rising formed a white cloud round’the sum- mit, and, being driven by the north-east wind, extended in a long stream to the island of Capri. By night repeated eruptions of fire were visible, though no subterraneous explosions were to be heard at Naples ; and a tract of ground to the south of the crater assumed a dusky red colour, which, by the experienced in volcanic phenomena, was said to be preparatory to the flowing of the lava. I should immediately have repaired to the place, had not my friends at Naples assured me, from the practical knowledge they had of their burning mountain, that that eruption, which at my arrival was but inconsidera- ble, would after some time become much more extensive. It was in fact my wish to see Vesuvius, if not raging with its most tremendous fury, at least in a more than ordi- nary commotion.
i} I, in consequence, returned from Sicily to Naples in the beginning of November, when a stream of lava, issuing from an aperture in the side of the mountain, covered a considerable extent of ground, and began to be visible before day-light, from beyond Capri, under the appearance of a streak of a reddish colour. On the 4th of the same month I began my journey to the volcano, and ‘passed the night at the Hermitage’ del Salvatore, two miles from the summit of the mountain. Before I retired to rest, I passed several hours in making observations with the greatest attention ; nor could the oppor-
fo} tunity have been more favourable, as there was no moon, and the sky was perfectly free
|. from clouds. I had therefore a clear view of the eruption of the mountain, which had’the appear-: ance of a red flame, that enlarged as it rose, continued a few seconds, and then disap- ©
RRR area SR RE A LE A es
IN THE TWO SICILIES, 13
peared. The ejections succeeded each other at unequal intervals of time; but no in. termission continued longer than five minutes.
I rose four hours before day, and continued my journey towards the burning crater, from which, as I have before said, flames arose at intervals, which on a nearer approach appeared larger and more vivid; and every ejection was followed by a detonation, more or less loud, according to the quantity of burning matter ejected: a circumstance I did not notice before, on account of the distance, but which became mcre perceptible to the ear in proportion as I approached the mouth of the volcano; and I observed, when I had arzived within half a mile of it, in a direct line, that the ejections preceded their ac- companying explosions only by an instant, which is agreeable to the laws of the pro- pan of light and sound. At this distance not only flames were visible to the eye, |
ut a shower of ignited stones, which, in the stronger ejections, were thrown to a pro- |
a digious height, and thence fell on the declivities of the mountain, emitting a great ¢ ng quantity of v: vid sparks, and bounding and rolling till they came within a short distance t of of the place where I stood. These stones, when I afterwards examined them, I found for to be only particles of the lava, which had become solid in the air, and taken a globose rom form. ‘These showers of lava appeared an invincible obstacle to my nearer approach and . tothe volcanic furnace. I did not, however, lose all hope, being encouraged by the e of following observation. The showers of heated stones, [ remarked, did not fall verti- ne cally, but all inclined a little to the west. I therefore removed to the east side of Ve- y in suvius, where I could approach nearer to the burning mouth: but a wind suddenly springing up from the west, compelled me to semove, with no little regret, to a greater distance, as the smoke from the mouth of the crater, which before rose ina perpendicu- t in lar.column, was now drifted by the wind to the side on which I’ stood; so that I soon the found myself enveloped in a cloud of smoke abounding with sulphureous vapours, and 1 'to was obliged hastily to retire down the side of the mountain. Yet though I was thus y, it disappointed of the pleasure of approaching nearer to the edge of the crater, and observ- im- ing the eruptions more nearly and accurately, many instructive objects were not wanting. and But before I proceed to any remarks on these, I must notice a curious and unexpected . ous circumstance, ater T have already spoken of the detonations which accompanied the showers of lava. said It is now necessary to add, that these did not constantly accompany every eruption. the When I had taken my station in the lower part of the mountain, I found the detonations had more sensible, and resembling the noise produced by a large mine when it explodes; but era suddenly, to my great surprise, they ceased, though the ejections of fiery matter con- 1 to tinued both frequent und copious. I counted eighteen eruptions which were not accom- rdi- panied by the smallest noise. The nineteenth, though not larger than the former, was followed by its detonation, as were eleven more, though others which succeeded were ber, silent. ‘This irregularity I observed so repeatedly, that the detonations appeared to me da rather accidental than necessarily connected with the explosions. In this opinion Iam ond supported by the authority of my ingenious friend, the abbe Fortis who afterwards told : ame me, at Naples, that he had frequently observed the same inconstancy in the eruptions of del Vesuvius. +B ds 8 ,; sed “This peculiar phenomenon, which has not, tomy knowledge, been remarked by any or- one of the numerous authots who have written on Vesuvius, does not appear, at first free view, to be easily explicable from the physical cause of the explosions, As it. must be allowed that the fire alone is not sufficient to produce it, we must have recourse to an ear: elastic fluid, which disengages itself from the lava, impelling at the sametime.a part of
ap." it into: the, air;..which. effect can scarcely happen without a detonation. But on more
a ee
ae ene ee
b+ SPALLANZANI’S TRAVELS
mature reflection it appeared to me most probable that this takes place only within cer. tain limits, When the elastic fuid bursts suddenly against the lava, it isto be expect. ed that it will produce a considerable report; but when it acts slowly it will occasion little or none, though the ejection may be very strong. Thus, if the atmospheric air be confined between two pellets of tow in.a tube, and one of them be forced suddenly to- wards the other, the latter will be projected to some distance, with a considerable sound, but none, or very little, will be heard if the pellet be gradually pressed towards the other. In like manner the air contained in an air gun produces scarcely any report on ita, secant, on account of the interposition of the valve delaying its action on the pall,
In what I have said, however, Ido not mean to assert that these volcanic eruptions Were cntirely unaccompanied with any explosive sound. It is highly probable they were not; but that I could not hear the feebler detonations on account of the distance.
It has been already said, that the liquid lava had opened itself a way, not immediate- ly from the summit of the crater, but ! »m one side of the mountain. The followi are the observations made on this subject. ‘Towards the south-cast, at the distance o about half a mile from the crater, on a declivity, there arose sixty or more small columns of smoke, one of which was, about nine feet in diameter, and came from a:not very dee cavern, The ground from which these streams of smoke issued was tinged with yel- low, from the muriate of ammoniac, and so hot, that even at some distance, I could bear my feet on it only for afew seconds. It is sufficiently manifest that the smoke and heat proceeded from the same cause ; that is to say, from the subterrancous conflagra- tion which communicated with that part, and caused the smoke to burst forth through the fissures in the ground.
At the distance of a few paces from this spot, the aperture was visible through which, six months before, the laya disgorged itself, as 1 was assured by my guide; but it no longer flowed at the time of my arrival, its current having acquired the hardness of stone, About fifty paces lower, however, in the same. direction, that is towards the south, the lava was still running within a kind of pit, but without rising, above. its bor- ders ; andat a place still lower, about two miles from the principal crater of Vesuvius, the lava leaned from the subterranean cavern, forming in the open air a long current. But before I pesrord to describe the latter, it will be proper to notice the highly curious phenomena observable, in the lava moving within the above-mentioned cavity or pit. This pit was of a shape approaching to an oval, about twenty-three feet in circuit. The sides, or banks, were nearly perpendicular, about four feet and a half in height ;, and it was excavated in the hardened lava of the last eruption. The burning lava moved with- in this cavern, of which it covered the whole bottom, in the direction of from north to south. From it arose acloud of smoke, which reflecting the light from the red hot lava, produced in the air a red brightness, that during the night might be seen at a consider- able distance. Butas this smoke was strongly impregnated with acid-sulphureous va- pours, I found it a great obstacle to my making any observations on the liquid lava, when, from the calmness of the air, it ascended)perpendicularly.. But, from. time. to time, a slight breeze arose which carried the stream. gowards one side; and I then re- moved to the opposite, where I was no longer incommioded in my experiments by the vapour. During these favourable intervals, I could stoop.down towards the pit,. in which I obs‘:eved the appearances which I here faithfully relate. .
At the distance between the lower extremities of my body and the lava was only five feet, the heat it sent forth was very vehement, but not absolutely intolerable, though it forced me to remove from it a little, from time to time. ’ —
IN THE TWO SICILIES. 15
I observed then that the lava flowed, as I have before said, along this cavity, from the north to the south, and then disappeared under the excavated hardened lava. Its sur- face exhibited the redness of burning coal, but without the smallest appearance of flame. I know nothing to which it can be more properly com thon melted brass in a fur- nace. ‘This superficies was in some places covered with a white froth ; and from time to time bubbles arose in it, which burst a moment after with a sensible noise. Sometimes, likewise, the lava rose in small jets or spouts, which, in an instant after, subsided, and the surface again became smooth and even,
The nearness of my approach to this melted matter, which I observed, first, during the darkness of the night, and afterwards by the light of day, removed every shade of doubt or uncertainty respecting the remarks I made. It likewise furnished me with an opportunity to make some experiments which I otherwise could not have made. I was desirous to let fall some heavy body into the flowing lava; but my situation would only permit me to use, for this purpose, pieces of lava which lay round the cavern, as I could find no substance of any other kind. When I threw these pieces into the lava, they occasioned that dull kind of sound which would have been produced by strikin soft earth or thick mud; and at the same time formed in the lava an incavation, in whic they were buried about one third of their bulk, and in this situation were carricd away by the current. The same happened when I, at other times, used larger picces, and threw them forcibly into the lava; the only difference was that then they sunk in deeper.
rom this experiment I ascertained the velocity of the lava, as it is certain that must have been the same with that of the stone carried by it. In about halfa minute, the pieces of solid lava were carried ten feet and a half. The motion of the current was therefore very slow; which was not surprising, as the declivity was very little. We shall see presently, that the pieces of lava with which I made my experiment, were probably of the same kind with the lava which was wit on which account J, at first, ex- pected that they would have sunk entirely within it, since it is well known that all bo- dies which pass from a fluid to a solid state become more compact; but a moment’s reflection convinced me that the fact could happen no otherwise than it did. The pieces of lava which I threw into the current were full of pores and cavities, which in the liquid lava could not have place, or at least could not be so numerous ;_ these pieces, therefore, must be lighter than the liquid lava. Another reason, which I consider as still more decisive, is derived from the tenacious liquidity of the flowing lava, which must prevent the entire immersion of the solid lava, though the latter should be specifically heavier. Thus I have observed that a solid globe of glass, though thrown with some force into a liquid mass of the same matter, will not remain entirely submerged, but float with a
above the surface.
I would willingly have made another experiment, which I should have considered as of much greater importance; but I had not with me the instruments necessary to undertake it; because I had not the least expectation that I should have been able ) approach so near to the owing lava as would have given me an opportunity to have used them.
The experiment I mean was to have ascertained the degree of absolute heat of the flowing lava, and might have been very conveniently made at tts place. As therefore circumstances did not permit me to make a second visit to Vesuvius, and as these cavi- ties which receive into them the flowing lava are frequently met with in volcanic erup- tions, it may not be improper here to detail the nature and mode of the experiments I would have made, had I been furnished with the necessary means, in hope that some
oe Re =
16 SPALLANZANI'S TRAVELS
similar opportunity may induce some one of the few naturalists of Naples who are de- sirous to enlarge the knowledge we have of their volcano, to carry them into effect.
First, therefore, I would have let fall on the lava within that cavity two kinds of substances, inflammuble and fusible, contriving some means to keep them fixed in the name place; punctually noticing the time required for the inflaming of the former and the fusion of the latter. I would then have exposed the same substances to our com- mon fires, until the same effects had been produced, observing the difference of time between the production of the effect by the volcanic fire and the common. I should thus have obtained a term of comparison of great utility in the inquiry proposed. But a method more precise and pe would be to make use of the pyrometer of Mr. Wedgwood ;* which should be used in the following manner; to ascertain the abso- lute heat of the superficies of the lava, one or more of the cylinders of clay should be let down upon it, inclosed in the box of the same earth adapted to them, fastened to an iron chain that it may not be carried away by the current, and the experiment pre- vented. ‘This being taken up, after having been suffered to remain there some hours, the shortening of the cylinders would shew the quantity of absolute heat they had suf. fered, and, consequently, that of the lava on which they had rested.
But with this experiment alone I should not have been entirely satisfied. By the assistance of this same pyrometer, I would have endeavoured to discover the internal ab- solute heat of the lava, by immerging within it some of the cylinders I have before men- tioned, inclosed in a thick hollow globe of iron, fastened to a chain of the same metal. The infusibility of iron in our common furnaces inclines me to believe that it would re- sist the heat of the liquid lava; but should it nct, its melting would supply the place of a : diapeend: and sufficiently prove the violence of the heat.
am aware that these experiments would not ascertain, with precision, the heat of other torrents of lava, which must necessarily depend on the greater or less depth of the ignited matter, its distance from the principal seat of the conflagration, and the dif- ferent qualities 0: the lava. But they must have been of considerable importance, and Ican never sufficiently regret not having had it in my power to make them.
It may, perhaps, be doubted whether the globe of iron I have mentioned could be made to penetrate through the tenacious superficies of the lava: but there seems little reason for this doubt, when we consider that the pieces of porous lava, which are far lighter than this metal, penetrated it to one third of their bulk. And though it should not be able to divide that part of the superficies which, by being in contact with the air, has less Bquidity 5 that might be separated by other means, and the globe imme- diately plunged into the more fluid part. of the lava.
I do not deny but that these and other similar experiments are difficult, offensive, and, in some degree even dangerous ; but what experiment can be undertaken perfectl free from inconvenience, and all fear of danger, on mountains which vomit forth fire I would certainly advise the philosopher who wishes always to make his observations en- tirely at his ease, and without risk, never to visit volcanos,
But it is time to continue my narrative of the phenomena I observed in this eruption of Vesuvius. Though the lava issued at its origin from only a narrow aperture, ‘the stream of it became considerably enlarged as it descended the declivity of the moun- tain, and formed other smaller torrents: but at about the space of a mile from the mouth whence it issued, its superficies had acquired the solidity of stone. I endea- voured to pass over this, notwithstanding the dificulty of walking on it, as it was en-
* See the Introduction.
IN THE TWO GICILIES. Ly
tirely composed of small disjoined scoris, on which the foot could not rest with firm. ness, and so hoi that I was obliged to change my shoes, those I had being worn out, and half-burnt.
Besides two other pits, similar to that I have described, and some burning orifices in which, when I looked into them, I could perceive the liquid lava resembling melted glass in a furnace when it burns with the utmost violence ; I observed, likewise, the traces of the course which the lava had taken or resumed. Here the channels through which it had flowed remained, but empty; there some residue of it was to be seen ; and others were full of it. One had the form of a cylindric tube, and another that of a parallelo- piped. But the direction of all these channels through which the lava had flowed was towards the south, It did not require much attention to perceive, that under the solid lava on which I walked the fluid was still running; the low but distinct sound it occa- sioned in its passage was clearly perceptible to the ear.
A sufficient illustration of what I mean may be given from what frequently happens, in winter to many slow streams, in the northern parts of Italy. In these, when the winter is severe, the superficies of the water at first adheres to the banks, and afterwards congeals in the middle, forming a crust of ice which increases in thickness, from night to t, while the water, which is still fluid, if there is sufficient depth, continues to run under it; though the thickness of the ice increases, till after some days it is suffi. ciently strong to bear men to walk on it, or even ter weights. If any person should then go upon it, and apply his ear close to it, he would oe the sound of the water running under, as I have several times experienced in the vicinity of Pavia. This sound appears to me to be precisely the same with that occasioned by the Vesuvian lava flowing under the solid lava, and proceeds doubtless from the same cause ; I mean the abn the fluids meet with and strike against in their passage ; as the cause of conge- lation is likewise the same in both, that is, the privation or rather the diminution of their absolute heat,
Pursuing my way to the south, along the declivity of the mountain, I arrived at the part where the lava ran above the ground. Where the stream was broadest, it was twenty-two feet in breadth, and eighteen where narrowest. The length of this torrent was two miles, or nearly so. This stream of lava when compared with others which have flowed: from Vesuvius, and extended to the distance of five or six miles, with a proportionate breadth, must certainly suffer in the comparison ; but considered in itself, and especially by a person unaccustomed to such scenes, it cannot but astonish and most powerfully affect the mind. When I travelled in Switzerland, the impression made upon me by the Glaciers was, I confess, great; to see in the midst of summer im- mense mountains of ice and snow, placed on enormous rocks, and to find myself shake with cold, wrepped up in my pelisse on their frozen cliffs, while in the plain below na- ture appeared guid with the extreme heat. But much more forcibly was I affectsd at the sight of this torrent of lava, which resembied a river of fire. It issued from an aperture excavated in the congealed lava, and took its course towards the south. For thirty or forty paces from its source, it had a red colour, but less ardent than that of the lava which flowed within the cavern I have mentioned above. Through this whole space its surface was filled with tumours which momentarily arose and disappeared. I was able,to. approach it.to within the distance of ten feet ; but the heat I felt was extremely
almost insu ble, when the air, put in motion, crossed the lava, and
w,upon me. When:I threw into the torrent pieces of the hardened lava, they left
a very slight hollow trace. Thesound they produced was like that of one stone striking against another ; and they swam following the motion of the stream. The torrent at
VOL. V. D
18 GPALLANZANI'S TRAVELS
first descended down an inclined plane which made an angle of about 45 degrees with the: horizon, flowing at the rate of cighteen fect in a minute; but at about the distance of thirty or forty paces from its source, its superficies, cleared from the tumours I have before mentioned, shewed only large flakes of the substance of the lava, of an extreme- ly dull red, which, clashing together, produceu a confused sound, and vc borne along by the current under them,
Observing these phenomena with attention, I perceived the cause of this diversity of appearance. The lava, when it issued from the subterranean caverns, began, from the impression of the cold air, to lose its fluidity, so that it yielded less to the stroke of solid boulies, The loss of the principle, however was not such as to prevent the superficies from flowing. But at length it diminished by the increasing induration ; and then, the —_— part of the lava, by the unequal adhesion of its parts, was separated into
es, which would have remained motionless had they not been borne away by the sub- jacent matter, which still remained fluid, on account of its not being exposed to the im- mediate action of the air, in the same manner as water carries on its surface floating flakes of ice.
Proceeding further, I perceived that the stream was covered, not only with these flakes, but with a great quantity of scorie ; and the whole mass‘of these floating mat- ters was carried away by the fluid lava, with unequal velocity, which was small where the declivity was slight, but considerable when it was great. In one place, fur ten or twelve feet, the descent was so steep that it differed but little from a perpendicular. The lava must therefore be expected there to form a cataract. This it in fact did, and no sight could be more curious. When it arrived at the brow of this descent, it fell headlong, forming a large liquid sheet of a pale red, which dashed with a loud noise on the ground below, where the torrent continued its course.
It appeared to me that it might be expected that, where the channel was narrow, the velocity of the torrent mans be increased, and where it was capacious diminished ; but I observed that, in proportion as it removed from its source, its progressive motion became slower; and the reason for thic is extremely obvious; since the current of melted matter being continually exposed to the cold air, must continually lose some. portion of its heat, and consequently, of its fluidity.
At length the lava, after having continued its course about two miles, along the de- clivity of the mountain, stopped, and formed a kind of small lake, but solid, at least on the superficies. Here the fiery redness disappeared; but about two hundred feet ped it was still visible, and more apparent still ‘nearer to its source. From the whole of this lake strong sulphureous fumes arose, which were likewise to be observed 7 a sides where the lava had ceased to flow, but still retained a considerable degree
eat. - After having written these observations on the lava ejected by Vesuvius, as it ap- peared trom its source to its termination, which I made in company with Dr. Comi Abruzzese, a young student of great promise in medical and physical science, I had an opportunity to read the accounts of former eruptions, as they have been given by men of great abilities, who had observed them on the spot, I mean Dr. Serao, Father Della Torre, M. Deluc, and Sir William Hamilton. I perceive that in the principal facts, the phenomena I have observed agree with their observations, and that the differences are but few. Thus the torrents of lava which they have described were, accompanied with great fumes, and covered with pieces of laya and scoriz. In like manner the liquid lava received but small impressions from the stroke of solid bodies, and some- times none. Serao informs us, that ‘the lava of 1737, when struck on the surface
IN THE TWO GICILIEG, if
with long pointed staves, was found to be so hard that it resounded. According to the observation of Father Della ‘Torre, the thick lava of the eruption of 1754, when raised with iong poles, split into pieces. M, Deluc shewed me, some years since, in his pri- vate cabinet of natural history, at Geneva, a piece of Vesuvian lava, of the eruption of 1758, marked with a slight impression, which he made on it, on the spot, while it re- tained its softness. If this naturalist should ever chance to come to Pavia I could shew him, in return, in the public Imperial Museum, among the collection of volcanic pro- ductions which I have made, a cylinder of lava, eighteen inches long, and five and a half thick, which, in one part, has been bent to an angie, while it was half liquid, by the hands of the guide who accompanied me when I visited the eruption I have above de- scribed. In the eruption of 1766, likewise, though the lava flowed with su rising ve- locity, we are told by Sir William Hamilton, that it received but a very slight impression from some large stones that he threw into it, Father Della Torre has also remark another phenomenon which I observed, and have described, relative to the effervescence and tumours of the fluid lava.
But my meeting with the subterranean cavity in which the lava flowed, was a fortu- nate and singular circunistance, which is not, that I know of, mentioned by any one else, because prebably it was not sen; since all the descriptions of eruptions which we have, relate solely to currents of lava running over the surface of the ground, ex to the free action of the air; from the effect of which the lava must soon cool and harden ; as appears from the very slight impression made by stones thrown into it, according to all the accounts I have cited, and my own observations. But the narrowness ¢{ this cavern, and in some measure its depth, prevented this action of the air; whence I was enabled to observe the lava in a state in which it cannot be seen above the ground, still retaining a great part of its fluidity, as appeared from its from time to time spouting into the air, and from the impressions made on it by the pieces of lava thrown into it. It cannot, therefore, be doubted but it had a much greater degree of fluidity when it boiled up in the Vesuvian furnace; as it must then have been penetrated with a greater quantity of absolute heat, by the action of which its parts must have been more disjoined and sepa- rated, and therefore have possessed a‘yreater degrec of fluidity and mobility. But I shall adduce still stronger reasons to prove the great fluidity of the lava, when it foams and boils up in its craters, when I come to speak of the volcano of Stromboli. 1 dwell the longer on this subject, because I know some have denied that the lava is ever fluid, as- serting, that it has only the consistence of paste moistened with a good deal of water, and descends down any declivit in consequence of its gravity.
To complete the observations I have made on this eruption, nothing appears to remain but to speak of the quality of the ejected lava. On this I made different experiments, all of which, some extrinsic or accidental circumstances excepted, furnished the same results. The base of the lava is of horn-stone rock, of a dark-gray colour, of moderate hardness, dry to the touch, where it has been fresh broken somewhat earthy, and gives
‘some sparks with the steel. This lava put the magnetic needle in motion at the distance of three lines and a half, or somewhat more than a quarter of an inch, A “It is well known to volcanic naturalists, that many of the lavas of Vesuvius contain colourless garnets. In that of which I treat, they were found very numerous, though v-ry small, When broken, any appeared lassy ; and sometimes a kind of side or face was visible, though without its being possible to determine the quality of the crystalli- zation, not so much from their smaliness as from their being too intimately incorporated With their tenacious matrix. With the garnets were united a number of shoerls, of the _ colour and lustre of asphaltum, vitreous crystallized in faces, the largest of which. was / a 4 $ : D 9 ’ iy
{
20 SPALLANZANI’S TRAVELS
nearly five lines, ‘Those which were found in the running lava had received no injury from the fire ; but those in the globes ejected from the crater in that eruption, were in a state of beginning fusion.
The fire of the furnace changed this lava into a kind of enamel, full of bubbles, of the colour of pitch, shining, which gave sparks with steel, and adhered strongly to the sides of the crucible.* The shoerls melted, but the garnets did not; they only became whitish, but without entirely losing their vitreous appearance.
After having made my observations on the phenomena exhibited by the stream of lava then running, I proceeded to examine the vestiges of others which had flowed some time before; one of which, in November 1785, had issued at about one third of a mile from its crater, on the side of Monte Somma. As Ido not know that any notice has yet been taken of it by others, I shall relate the observations I made as [ passed over the remains of it, and likewise the information given me concerning it by my guide, and some persons who cultivate the study of Natural History, who had observed it on the spot at the time of its eruption.
Although at its source it was but narrow (as generally happens to these streams of lava) it afterwards became considerably enlarged, and did not form small, disjoined, and rugged pieces like the others I have described; but large masses, many feet in breadth and depth, and separated by numerous fissures. Its superficies presented an appearance not a little curious. It was rugged and irregular, from an immense number of small cylindric bodies resembling twisted cords, and which are only the lava itself re- duced into striated and contorted fibres, when near the end of its course, and ready to congeal, In its qualities it did not appear to me to differ from the other Vesuvian lava I had already examined, either in its base or the garnets and shoerls which it contained.
The greater part of this lava lies in a valley under Massa, and on one side of Salvatore. Before it arrived there, it must have fallen from a high rock, and consequently formed a cataract, which, when seen by night, I wastold, exhibited a most wonderful spectacle to the eyes of beholders, But though its fall through the air must have been very con- siderable, and it must in consequence have lost much of its heat, when it reached the ground it continued still to flow for a considerable space. On the side of Massa, I ob- served that it had approached within ten or twelve feet of some oaks which grew on the side of a precipice. Some of them appeared entirely withered; others preserved their verdure only on that side of the trunk and branches which was opposite to that next the lava. In its passage it did such damage toa small church called Madonna della Vetrana, that it has ever since remained deserted. The fiery torrent took it in front, and broke down the wall, which indeed required no great force, as it was built with soft stones of tufa brought from the neighbouring mountains of Massa, and much like that of Naples. ‘Thence it penetrated into the church, and having destroyed the door.on the opposite side, and beat down a part of the wall, continued its course, through the church, within which it was observed to flow with greater velocity than the rest of the surrounding lava, from being confined by the walls on the sides. With this lava the floor of the edifice still continues covered, and the contiguous sacristy partly filled; while large pieces of the broken wall, which the torrent had carried away, lie at more than eighty feet distance from the church, in the middle of the hardened lava. Some linden trees
* To avoid repetitions, I shall here mention, that, when I use the word furnace without any other addition, I always mean the furnace of a glass-house; and that by the term enamel, I understand, with the generality of our chemists, a substance produced by heat, resembling glass, but without its transparency. It may also be proper to add, that, as often as an entire fusion of the lava took place in the crucibles, it adhered strongly to the sides.
a a a te ee RR CR TNS Re OEY A, Leena:
IN THE TWO SICILIES. 21
yury are likewise to be scen surrounded by the same, the trunks of which are blackened and re in burnt. The lava, as I was assured, continued to flow fiftcen months ; and when I visit- ed the place, which was ten months after it had ceased to flow, it was stili warm, and s, of emitted thin fumes. o the On one side of Vesuvius, about a mile below Salvatore, is a spacious cavern, which came widens as we descend into it, called the Fossa Grande. I took this way to return to Naples, and gained from it considerable and useful information. It is well known what m of doubts have been entertained relative to the shoerls and feltspars which are usually some found, either conjointly or separately, in the lavas; I mean whether they have bec: | ‘mile | formed within them, either while they were fluid, or at the time of their congelation; or 7 | 8 yet whether they existed in the pe ae rock before the fire changed it into lava. Bergman | 4 the has stated the arguments on each side, but has lef. the controversy undecided. It is true, and that, when that chemist wrote on volcanic productions, the opinion was, with good rea. n the son, most prevalent, which supposes that the shoerls and feltspars existed originally in the primordial rocks. This hypothesis has received considerable support from the ns of pieces of rock anciently thrown out of Vesuvius, which are to be found on the surface ined, of the ground; or by searching and digging in the tufaceous matters of the Fossa et in Grande. ed an But it is necessary to proceed to particulars. One species ofthese rocks is of a mar- mber gaceous nature, the carbonate of lime however prevailing. As this did not appear to be If re- at all calcined, but unchanged, and similar to stones of the same kind which are not vol- dy to canic, it afforded a convincing proof that these rocks have received no sensible injury n lava from the fire ; but if we break some of these, we shall find in them numbers of feltspars, ‘ined. which, in their crystallization, and other exterior characters, extremely resemble many atore. of those we meet with in some lavas of Vesuvius, and other neighbouring volcanic ned a places. Still more numerous also are the shoerls of a shining black ; some of the shape ctacle of needles, and others of prisms, and varying in their size; some being so small as tr "'e - con- scarcely visible, and others of the length of seven lines, or above half an inch, and bread d the in proportion. These pieces of rock do not form veins, strata, or great masses, but are I ob- distributed in different places in scattered fragments. | yn the Here likewise we find various pieces of granite, not in the least injured by the fire ; | their the quartz of which, besides mica, is accompanied by feltspars and shoerls, which in no | xt the : respect differ from the volcanic shoerls and feltspars. trana, I spa have considerably extended these remarks on the species of rock thrown out broke by the Vesuvian fires without receiving injury or change; but I think that what I have nes of said will be sufficient to shew, that, in order to account for the presence of feltspars and aples. shoerls in lava, and their various crystallizations, it is not necessary to suppose them posite formed within it, either when it was fluid, or at the time of its congelation; since we within meet with similar vitreous bodies in the substances from which it derives its origin. nding of the large eighty | 1 trees { y other rstand, hout its
k place
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SPALLANZANI’S TRAVELS
to t>
CHAPTER II.
THE GROTTO OF POSILIPO...SOLFATARA...THE PISCIARELLI.
The city of Naples founded on volcanic substances....Different opinions relative to the origin of volcanic tufas.... Those of Posilipo appear to have been formed by thick eruptions....Lavas on the road to Solfatara described....Specular iron found in one of these....Solfatara is not an iso- tated mountain, as has been supposed by some....Sulphures of iron (or pyrites) lavas of Solfata- ra, and the Pisciarelli....Observations on the decomposition of lava, Sod the shoerls and feltspars which are found within it; as also on the sulphureous-acid fumes which incessantly exhale from this volcano....Conjecture that Solfatara has arisen out of the sea.... Method lately employed to extract, more abundantly than formerly, alum and sal ammoniac from this volcano....Critical disquisition relative to a curious Lpecanipnigt in the vicinity of Solfatara, from which M. Fer- ber conjectures that the level of the sea has there sunk nine feet.
DURING my stay at Naples, I determined to visit the other principal Phlegrean fields, as well as Vesuvius, and I had the good fortune to meet with, and have for a companion, the abbe Breislak, formerly professor of philosophy at Rome, and of ma- thematics in the Nazarine College ; and now director of Solfatara, near Pozzuolo.
The beautiful city of Naples is entirely founded on volcanic substances. Among these the tufa predominates, which has also contributed not a little to the materials of many buildings. To the north and west it is accumulated in large heaps, and forms spacious hills. A philosophical stranger, on his arrival in this country, when he views these immense masses of a substance which must excite in his mind the idea of fire, can- not but feel astonishment, and inquire with a kind of serious thoughtfulness, what has been their origin. It is known that on this subject naturalists are divided. Some con- jecture that the volcanic tufa was generated within the sea when it bathed the foot of the burning mountains ; others suppose that the cinders ejected by the fire have, in a long course of years, been hardened into this species of stone by the filtration of rain water ; lastly, others incline to think that the tuf. derives its origin from the slimy and fluid substances thrown out by the volcanos in some of their eruptions.
The diversity of volcanic tufas has perhaps been the cause of these different opinions, each of which may possibly be true with respect to different kinds of tufa. -Those, however, which are found in the vicinity of Naples are probably the produce of thick cruptions, as we may conclude from the curious discovery of Sir William Hamilton, who, in digging up in the tufa which had covered Herculaneum, the head of an ancient statue, observed that the perfect impression of the head was visible in the tufa, which cannot be supposed to have happened but by its having enveloped the statue in a liquid or moist state. pa
To the observation of Sir William let me be permitted to add one of my own, which I made in the grotto of Posilipo. It is well known that this grotto has been excavated within the tufa, and serves asa public road from Naples to Pozzuolo. This tufa, which is of a clear gray, has for its base an earth in part argillaceous, of a slight hardness, which contains vitreous flakes, pieces of feltspars and fragments of yellowish pumice- stone, which by the changes it has undergone has become extremely friable, and almost ‘reducible to powder.. This tufa has been in some measure analysed by the excavation made in it by art, which furnishes a proof of the nature of its origin. | For if any person,
IN THE TWO SICILIRS. 25
in the summer time, enters the grotto about the rising of the sun, since at other times of the day there is not sufficient light, the solar rays, shining on the entrance which looks towards Naples, will sufficiently illuminate the roof and sides to shew laye.’s or lakes, similar to those which may be observed on the steep sides of mountains, or in perpendicular sections of the earth, in low places, where sediments of various kinds of slime have been formed by the inundations of the rivers. It seems, however, impossible to doubt that this accumulation of tufa, through the midst of which the Romans opened
gin of that long and spacious grotto, has been produced by the thick eruptions which have
as on frequently issued from volcanos, and which, heaping up one upon another, have har- | leo dened in time into this tufaceous stone; since both Vesuvius and Etna furnis‘: sufficient | pitata-
examples of such eruptions. And as in many other tufas in the vicinity I have observ-
pars ed a similar constructure, I cannot suppose their origin to have becn different. Awe Coming out of this subterraneous passage, and proceeding towards Solfatara, I ob- ritical served, on the right hand side of the road, a ridge of lava, nearly parallel with it, which Fer- had every appearance of having been thrown out of the volcano when burning, both because it was extremely near to it, and had its highest part in that direction. Its thick- ness exceeded five-and-thirty feet, and it was situated between two layers of tufa, onc | grean above and the other below. It formed a high rock, perpendicular to one side of the for a road. A number of labourers were continually employed in separating pieces of this y ma- lava with pick-axes, or other instruments proper for such work. It is compact, heavy, somewhat vitreous, gives sparks with steel, and appeared to me to have for its base the mong petrosilex. Incorporated with it are found shocrls and feltspars. ‘The former are shin- als of ing, of a dark violet colour, in shape rectangular needles, vitreous, in length from the forms sixth of a line to two lines: it besides contains a considerable quantity of others which views have no regular form. But the feltspars are more conspicuous than the shoerls, both ', Call- from their larger size and greater number. They are in general of a flat rhomboidal at has form, and consist of an aggregate of small white lamellz, duly transparent, brilliant, e con- marked with longitudinal streaks parallel to each other, closely udhering together, but of the easily separated by the hammer, giving sparks with steel more readily than the lava ; and, . long in the full light of day, exhibiting that changing colour which usually accompanies this | vater ; stone. The largest are ten lines long and six broad, andthe smallest exceed one line. | fluid The shoerl|s are also found in the lava, in the same manner, and are so fixed in it, that they occupy nearly the half of it. Itis impossible to extricate them entire. They arc nions, distributed within it without any order, and frequently croys and intersect cach other ‘hose, at right angles. thick In some situations of this lava, which are more than others exposed to the inclemency nilton, of the air and seasons, the feltspars are visible on the superficies, by a mixture of emerald ncient and purple, probably occasioned by the action of the atmosphere, as from the same cause which some volcanic vitrifications acquire externally their peculiar colour. liquid - ‘This lava has not equal solidity throughout, being in some places porous, or rather ( cavernous ; and, in some of its varieties, it was remarkable, that it abounded with spe- which cular iron. This was found in very thin leaves, for the most part, closely connected avated together. These are extremely friable; and the finger being passed over them, they | which re'to it like particles of mica. But their small size, which in the largest is scarcely dness, a line, renders it necessary to make use of a lens to examine them properly ; by the aid | imice- of which we shall find that they are of very different shapes, have the lustre of burnished | almost steel, and that many of them appear to be gate of small thin scales, closely united. vation « This iron acts on the magnetic needle, at the distance of two lines. Like many other Merson, irons exposed to the air, it has acquired polarity; attracting the needle on one side,
and repelling it on the other.
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24 SPALLANZANI’S TRAVELS
When we extract these thin scales of iron from the lava, and examine them with the lens, there frequently appear, intermingled with them, various fragments of microscepic transparent prisms, which I at first thought to be shoerls of feltspars, but which after- wards I rather conceived to be zeolites, as they exhibited the appearance ef radii diverg- ing from their centre; but their extreme minuteness rendered it impossible accurately to ascertain their species.
Proceeding along the road to Solfatara, we find on the left hand a natural ridge of rock, formed of a very light lava, the base of which is horn-stone, of the colour of blue baked brick, of a coarse earthy grain, which attaches slightly to the tongue, and gives an argillaceous scent on wetting it, or even merely moistening it with the breath.*
It is very probable that this lava has been decomposed, and that the decomposition has pehettieed to the feltspars with which it abounds, as they are become very friable, though they in general still retain their natural brilliancy.
Having made these cursory observations, I proceeded to Solfatara: nor did I satisfy ~ysclf with one visit only, but repeated it several days; being extremely desirous care- ty to examine, and gain every information relative to a place so celebrated.
rom reading the notes of M. Dietrich to M. Ferber’s Travels in Italy, I had been induced to imagine that Solfatara was a mountain isolated on every side ;¢ but the truth is, it is connected with the other neighbouring mountains, with which it forms an un- interrupted chain of considerable extent.
It would be tut of little utility for me to describe at length the form, extent, and cir. cuit of this Phlegrean field ; the various qualities of the hot vapours which exhale from it; or the hollow noise which is heard on striking the ground in various parts of it; not that these circumstances were not carefully examined by me; or that I think them unworthy of my narrative ; but because it appears to me unnecessary to enlarge on them, as they have been already repeatedly described by a great number of travellers. It will, in my opinion, be more agreeable to the naturalist to proceed to a minute exa- mination of the principal productions of this yet unextinguished volcano, as they have hitherto been, for the most part, either unobserved, or passed over in silence.
In the obscurity 2rd uncertainty in which we find ourselves, relative to the causes pro- ductive of subterrancous conflagrations, the spontaneous inflammation of sulphures of iron (or pyrites) has been considered as one of the most probable. The well-known experiment of Lemery, by which a similar conflagration is produced by mixing filings
.. ofiron with powdered sulphur properly moistened, has given great support to this opi-
nion. But sulphures of iron, in volcanic countries, are less frequent than has been supposed. This has been clearly proved by the accurate observations of mineralogists who have written on them. And though Sir William Hamilton expressly afirms that both Etna and Vesuvius abound with them,} it is now well known ht he mistook the shoerls for sulphures of iron (or pyrites) from want of mineralogical kncwledge. In fact, Signior Dolomieu, in his Catologo Ragionato de’ Prodotti dell? Etna, mentions only one single piece of lava as containing sulphur of iron; and the Chevalier Gioeni, in his Litologia Vesuviana, has never noticed any such production. In Vulcano and Stromboli, two islands which are in a state of actual conflagration, I could trace no vestiges of such
* In many lavas the scent of clay is perceived, on moistening them with the breath, or by other means: whenever, therefore, I may hereafter mention the argillaceous scent of lava I always understand it to have been subjected to this humectation, though I omit to mention it, to avoid prolixity.
+ La Solfatare represente encore aujourd’ hui une montagné assez elevee et isolee de tous cotes.” Lettres sur la Mineralogie, &c: d’Italie, &c.
{ Both these mountains abound with pyrites, Campi Phlegrai.
» * IN THE TWO SICILIES. Qh
sulphures, as will be remarked in the proper place. As the same kind of substance, therefore, is found diffused in several parts of Solfatara, I think it well deserves that we should carefully consider it, and the bodies with which it is found united.
I, The stones which I here undertake to describe are principally found in the interior sides of Solfatara. The first I shall mention exhibits, both externally and internally, a number of shining particles, which, when examined by the lens, appear to be small ag- gregates of sulphur of iron, some crystallized in cubes, others in globes, and others in irregular figures. When the flame of the blow-pipe is applied to them, they begin to lose their yellow colour, which quickly, in consequence of their destruction, entirely dis- appears ; when an odour slightly sulphureous is emitted.
This substance is a lava, the base of which is horn-stone; in part decomposed, light, friable, granulous, and of a cincreous colour.
II. The small sulphures of iron in this second lava are less numerous, but in their qualities very analogous to that already described; except that they are less decom. posed, and less friable.
III. The appearances exhibited by this lava aretwo. The external part is extremely white, and so decomposed, that the slightest blow reduces it to powder ; we likewise find in it some of the external characters of ordinary clay. It tenaciously adheres to the inside of the lip ;_is soft to the touch, and becomes still more so when slightly moistened. It absorbs water greedily, and with a kind of hissing noise ; but is not reducible to a lubricious paste, as clay is. But the internal part of this lava, besides being of a gray colour, is three-fourths heavier, and in its compactness and its grain, approaches to that species of calcareous earth, called calcareus zquabilis, though in fact it only resem - bles it in appearance, not being reduced to calx by'fire, nor dissolved by acids. | In this lava the sulphure of iron is not found in cubes, or globes, but in thin lamellz ; and is dispersed throughout its whole substance, especially in certain parts, where the colour of the stone inclines to black, and has a greater consistency. No sign of this mineral ap- pears in the white decompounded lava, probably because it was destroyed gradually, in proportion as the decomposition took place.
1V. This lava is much heavier than the three preceding ; which, no doubt, arises from the greater abundance of sulphure of iron that it contains. The shining particles of this mineral are principally to be seen in the vacuities (of which, however, it has not many.) They are polyhedrous, but the number of their faces is not constant. When exposed to the fire it loses its brassy colour, burns with a thin blue flame, and emits a strong smell of sulphur. The lava which centains it, and which is of a livid gray co- lour, is, in some situations, so soft that it muy be scratched with the nail, but in others much harder, and some of it will give sparks with steel. In this lava, the base of which appeared to me to be horn-stone, we find crystallized feltspars, but decomposed, though less so than the lava in which they are inclosed.
V. Around the extensive plain of Solfatara, we observe in several places a circular ridge of steep rocks, which once formed the uppér sides of this enormous crater. The rain-water, descending this declivity, over the decomposed lava, carries down with it the more minute parts to the lower grounds, where various concretions are produced, especially those stalactites which are commonly called oolithes, or pisolithes. But of these stalactites we shall speak hereafter. Here we shall only notice, that this water in its de- scent catries down with it small pieces of Gre ee d lava, and that in some places many of these pieces are found united, and bound together by a crust of sulphure of iron. It is black where it is exposed to the immediate action of the air, but in the frac.
tures of a shining appearance, though the colour inclines more to a lead coloyr than to VOL. v. _ &£
26 SPALLANZANI’S TRAVELS
yellow. ‘Its structure is scaly. The sulphures of iron which have before been men. tioned give fire with stecl; but this does not, from want of sufficient hardness. It abounds with sulphur ; since, being exposed to the flame of the blow-pipe, it visibly melts, and, the activity of the fire being increased, a blue flame arises, which continues till the crust is consumed, nothing remaining but a very smal! quantity of a white pul- verous earth, which is no other than a portion of decomposed lava, that had been united with this sulphur.
With this sulphur, the presence of which is extremely manifest from its strong smell is also united arsenic ; as sufficiently appears from the white fumes which arise from the combustion of the sulphure of iron, and which emit a very sensible odour of garlic.
These are the volcanic matters which, at Solfatara, aboundmore or less with sulphures ofiron. But whence is their origin? It is well known they are formed by the combt- nation of sulphur with iron, With the former this volcano abounds, whence it ob- tained the name of Solfatara ; and as the latter is almost always found mixed with vol- canic productions, which commonly derive from it their varying colours, we have thus the two proximate principles of sulphure of iron. But is their commendation effected by the dry, or, as is more probable, by the humid way ? I find it difficult to conceive how it can take place by the first method, on account of the speedy dissipation of the sulphur sublimed by fire, which must prevent its uniting with the iron to form these sulphures. It appears to me more probable that they have been formed by the action of water, which having penctrated the lava, the sulphur, dissolving in the fluid, has combined with the iron. Butas such solutions of sulphur in water seldom take place, as Bergman has observed, we rarely find sulphures of iron in volcanized countries, notwithstanding the existence of these two minerals.
But let us continue the description of the productions of this celebrated place, the
ater part of which are decomposed lavas; though this decomposition, notwithstand- ing it has been noticed by several writers, has not, to my knowledge, been examined by any one with requisite care and attention.
VI. This lava is coloured on the upper part with a covering of yellow oxyde of iron, ander which is a white decomposed stratum, to which corresponds another lower one of a cinereous colour, where the lava is much less changed. hese two strata form a very strong contrast. The white may be cut with a knife, in some places more’easily and in some less; adheres to the tongue, does not give sparks with stcel, feels soft to the wet finger passed over it, has considerable lightness, and being struck with a hammer gives a dull sound, like earth moderately hardened. On the contrary, the cinereous stratum sounds, when struck with a hammer, like a hard stone, of which it also has the weight; is rough to the touch, scarcely at all adheres to the tongue, gives fire with steel,
_and cannot be cut with the knife. The white stratum in some places is an inch thick,
ar.” in others more, but there are likewise places where it is only a few lines in thickness. + white stratum in general changes insensibly into the cinereous, but in some piaces \° separation is sudden and abrupt. ie feltspars in this lava (for of these it is full) are prisms, the largest of which are ten lines in length, and the smallest the sixth of a line. In the cinereous stratum, not- withstanding a beginning decomposition may be perceived, the feltspars are unimpaired. On the contrary, in the more decomposed stratum, I mean the white, their decomposi- tion is very apparent; they have all lost their transparency, though many of them still retain their splendour. Others have acquired a resemblance to a sulphate of lime that hasremained some time in the fire ; to which they’ ‘might likewise be compared in soft- ness, had they alittle less consistence. Some of them are infixed in that part of the
IN THE TWO SICILIES. 27
en: lava, the colour of which is between the cinercous and white, and here we find them less In changed than in the stratum which is entirely white. ‘Others have one part of them in bly the white, and the other in the cinereous stratum ; in which case we find the part fixed ues in the latter stratum to have suffered nothing, but that in the former considerably. In ul. short, from the inspection of this lava itis manifest, that, in proportion as the nature of ited it is changed, the feltspars it contains undergo a change, except when the principle pro- ducing the alteration is unable to affect them. Besides these feltspars, we find, incor. nell porated with the lava, a number of very small and almost invisible black shoerls, which the ure not distinguishable where the lava is white ; less, perhaps, because they do not exist, than because they have lost their colour in consequence of the decomposition. 1res This lava, which is of a margaceous base, does not liquify in the furnace, when its nbi- decomposition is considerable, but other parts of it, which have been less decomposed, ob- are reduced to a kind of frit. vol- VII, Solfatara, perhaps, does not afford a lava more compact, hard, heavy, or of finer hus grain than this.. Its composition is siliceous, its colour gray, it gives sparks strongly A by with steel, and, at the distance of two lines, attracts the magnetic needle. Its base is of how the petrosilex, and it contains within it different feltspars and shoerls ; but some of the phur latter have been melted by the fire, as appears from the bubbles or speckles occasioned ires. by the liquefaction. This lava is covered witha very white crust, nearly an inch thick, ater, produced by the decomposition it has undergone. The effects of the furnace on this with lava are nearly the same with those on the lava No. VI. 1 has VIII. This lava is entirely decomposed. On the surface, and for some depth, it is z the white, and almost pulverous; but in the internal part the white colour changes into a reddish blue, and acquires a degree of hardness, though not too great to be cut with a , the knife, The feltspars, in which it abounds, have suffered different degrees of decom- and. position. Some of them, besides being calcined, attach strongly to the tongue. Others, d by _ when viewed with a common lens, appear full of filaments, but when examined with a deeper magnifier, these filaments appear to be no other than extremely thin, striated, and iron, ~ very friable laminz. This production is infusible in the furnace. » one X. The feltspars in this lava occupy more than one third ofits mass. They are in om a shape flat prisms, and, except having somewhat less hardness, retain all the qualities sasily which characterise the species of stone to which they belong. There are also a number oft to of shoerls, which, from their extreme minuteness, appear like points, but are easily dis- wmer tinguishable, by their black colour from the lava, which is whitish, and has greater con- reous sistence than that of No. VIII. It is likewise heavier; to which the quantity of felt- 's the spars but little changed, which it contains, undoubtedly contributes. steel, ~ X. The shoerls which make so great a part of the other kinds of lava, are found so hick, _ Strongly adherent to them, that we usually can only separate them in fragments. The ‘ness. present lava, in this respect, offers an exception which may be considered as recommen- places datory of it. .. It has acquired sq great a degree of softness by its decomposition, that the numerous shoerls it contains may be detached from it entire. They are hexagonal +h are prisms, truncated perpendicular to their axes, the faces of which are slightly striated , Not- len wise, and their colour is a yellowish black. aired. »» Tn. this lava, the base of which appeared to me of horn-stone, another more remark. nposi- able. peculiarity presents itself. On breaking it, the fractures discover a number of small n still ) caverns, jewelled, if I. may employ the term, with a multitude of extremely minute e that Shoerls, of different colours, some green, some yellow, others of a dark chesnut, but n'softe all. similar, being hexagonal prisms, with rhomboidal faces, and each terminating in a
of the - dihedrous pyramid. ., Their angles are regular, their faces shining, and in part trans-
98 SPALLANZANI!'’S TRAVELS
nt. They sometimes form geodes in the body of the lava. To examine them a ens is necessary, and a good magnifier, clearly to perceive other shoeris still more minute. These are infixed in the small cavities I before mentioned, and, though they are extend- ed to a considerable length in front of the others before described, are so minute and numerous, that a single cavity will contain a hundred of them. Every one of both these kinds of shoerls has one extremity fixed in the lava, and the other in the air, and all together appear like a wood in miniature. I was, at first, in doubt whether I should consider them as shoerls or volcanic glass, as more than one instance has been known of such glass reduced to a capillary minuteness within lava. But the latter appeared to me improbable, because, after all the observations that have hitherto been nln we are not yet certain that any volcanic glass has been found crystallized; for, with respect to the pretended crystallization of some glasses in Iceland, we have not facts which demon- strate it incontrovertibly. On the other hand, the minute corpuscles I have described, if not all, at least those which from their larger size are more discernible by the eye, have a prismatic figure, and analogy must induce us to conclude the same of the rest.
I incline to believe these infinitesimal crystallizations produced, after the cooling of the’ lava, within the cavity in which they are found, from extremely subtle shoerlaceous sediments, by the filtration of water. But we shall have occasion to speak of similar ad- ventitious crystallizations within the substance of lava, in another part of this work.
XI. The oolithes, mentioned in No. V, lie in certain small channels of Solfatara, through which the water runs when it rains. They are either round, or somewhat flat- tened; rather more than half an inch in diameter, white as snow, extremely light, easily crumbled, and convertible into an almost a ge powder. ‘They adhere strongly to the tongue, and are composed of a number of thin scales. The formation, therefore, of this volcanic stalactites does not differ from that of the other species.
It would be superfluous to speak here of the sulphate of lime, adhering to some kinds of lava, or of the sulphate of iron, and the oxyde of red pie sah i arsenic, as these pro- ducti~ns of Solfatara have already been sufficiently examined and described by othersyg and I have no particular observations concering them which merit to be mentioned.
Hi XII. It is not uncommon to find at Solfatara pumices of various species; and it is i ti more probable that they have been thrown out of this volcano than from any of the 114 ‘others. We do not find them in great masses, as in other places, but in detached pieces and fragments. I shall only remark one particular relative to them, as it appears to me Ni] that in every other respect they perfectly resemble those already known. We now know that pumice is only a glass which wants but little of being perfect ; and seems to require only adegree more of heat to become such. The transition from glass less per- Hh | fect to perfect, may be perceived in some of these pumices in a very evident manner. In.some places their texture is fibrous, and the fibres are vitreous; but without that noi degree of transparency, which are inseparable from volcanic glasses. But following them
| with the eye, we perceive them consolidate, here and there, into masses of various sizes,
ed whick resemble a shining and smooth varnish, but are in fact perfect glass, as will suf-
it ficiently appear, if they be detached from the pumice, and examined separately. ‘These
q are sufficiently hard to give sparks with steel, a property observable in every volcanic
i) lass. i R Having now described the principal productions of the interior of Solfatara, I \t shall proceed to make afew observations on some ‘which are found in its exterior; in i that part which is next to the Pisciarelli, so called from the warm bubbling water, (i . @vhich issues, with some noise, from the bottom of a little hill contiguous to this volcano, + and which has been long celebrated for its medicinal virtues. I collected here speci-
m a ute, nd- and both dall ould own dto are t to on- bed, have
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' tara, t flat.
asily gly to re, of
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it is of the rieces io me
IN THE TWO SICILIES. 29
mens of five kinds of lava; but, asin their gencral qualities they are analogous to those already described, I shall ny Merge them in a cursory manner.
Kill. The first specimen is a simple or homogencous lava, in which, notwithstanding the most careful examination, I could not discover cither shoerls, felts or any ex. trancous body. In other respects, like those before mentioned, it is decomposed, ad. heres to the tongue, is friable, but without crumbling under the finger ; its whiteness extends through its whole mass, and wherever it is broken has the taste of sulphate of alumine (or alum.)
XIV. The second specimen, through acarly the half of it, exhibits a similar decom.
ition, and is of a white colour; but the other half, which is of a lead colour, has suf.
red little, gee sparks strongly with steel, and moves the magnetic needle at two lines distance. ‘This lava has for its base the petrosilex. Both that part of it which is slightly decomposed, and the other which is more so, contain rhomboidal feltspars, of which the a are about an inch in length. Their alteration is scarcely visible where the lava is least changed; and where it is more they exfoliate with some facility, but retain a considerable degree of their natural hardness and splendour.
XV. The third specimen is a lava of a dark gray colour, siliceous where fractured, very compact, and which gives sparks with no ay It is of a petrosiliceous base, and contains abundance of feltspars and shoerls. But to shew these, it is necessary to divest it of a thick, whitish, and half-pulverous crust, uced by its decomposition. In this pea wo shoerls and feltspars retain some consistence, but have lost, in a great degree, their lustre.
XVI. The fourth specimen contains within it a nucleus of a deep red colour, of the hardness and appearance of the carbonates of lime (calcareous earth) of a fine grain, but which is not dissolved or affected by acids, nor yields sparks with steel. It attracts the magnetic needle at the distance of one line. It contains a number of fissures, through which has penetrated, together with water, a quartzous matter, which has con- solidated into a semi-transparent, and somewhat FOU comers » In this lava, which is but little decomposed, are found, dispersed, a number of s masses of sulphure of won. 5
XVII. Small shoerls, and large eryentined ar iy oh occupy the substance of this last lava, which is somewhat porous, but sufficiently to give sparks with steel.
It is covered with a whitish yellow crust, which flakes off with a knife, and a reddish tincture has penetrated to its internal part, which is of a blackish ground.
In these lavas of Pisciarelli, the decomposition has, likewise, been much more con-
siderable, than in the feltspars and shoerls which they contain within them. . Ido not pretend to be certain that I have enumerated all the species of lava to be found at Solfatara: it is possible there may be others unobserved by me. I am persuaded, however, that I have described the principal; and such as enable me to deduce from their qualities the following conclusions.
I. -Almost all the species of lava, hitherto described, are more or less Genomipotes, and this decomposition is usually accompanied with a proportionable degree of whiteness.
This observation has been made by several authors; and first by Sir Willian Hamil- ton, and M. Ferber, who have endeavoured to account for the fact by a very plausible reason, which is, that the sulphureous acid vapours which issue from Solfatara, and must have been produced in an infinitely greater quantity when the soneegrine was at its height, penetrating the lava by de have insensibly softened it, given ita white colour. . And, in fact, similar sare observed to take place in a piece of black lava, exposed for a sufficient. time to the fumes of burning sulphur. But it does not
30 SPALLANZANL'S TRAVELS
hence follow that this Java will be changed into an argillaceous substance, as the above mentioned Swedish philosopher would have us believe ; since, from a chemical analysis, it appears that an carth of that kind, combined with other principles, pre-cxisted in it, and has only been rendered manifest by the diminution of aggregation produced by the before-mentioned vapours.
It is likewise not strictly trac that the walls, or amg | sides, of Solfatara are every where white and decomposed, as we might infer from the description of M. Ferber,
Those which look toward the south, indeed are so, but not those which are situated in another direction, and especially those which front the north, which are of a blackish co, lour, and little, or not at all, decomposed, The abbe Breislak, director of Solfatara, who accompanied me when I made my observations, suggested a very probable reason for this diversity of appearance in the different sides, observing that the sulphureous acid is less powerful to cflect the decomposition of lava, and requires longer time, when the lava has considerable humidity ; which humidity. must be much less on the southern side, where the heat of the sun is greatest. In fact, he exposed a piece of solid lava, to a ve humid sulphureous exhalation, at Solfatara, during two. months, without producing in it the least decomposition. \ II. The observations I have made convince me that the alterations here described al-
{
ways take place in the upper part of the lava; and that, in proportion as we penctrate if downwards into it, they become gradually less, and, at a certain depth, entirely cease. This, at first view, does not appear to accord with the effect of sulphurcous vapours, which, rising from the bottom of Solfatara, and passing through the lava, might be ex- i pected to cause a greater change in the lower parts than the higher, from their having Ni there greater heat, and consequently being more active. But we must consider that this may indeed be the nature of their action, where the lava is spongy, or at least very hi porous, but not where it is compact, and almost impenetrable to such vapours, as is i that of Solfatara. And, in fact, we find that the sulphureous fumes which arise there 4
do not issue from the body of the lava, but always from fissures or apertures in it, or the subjacent tufa. ‘These impediments, therefore, prevent them from acting except on the : ie surface, when issuing forth they are driven over it by the wind, and penetrating the lava, ina long course of time, produce the changes in question, We meet with few decom- osed lavas, within which we do not find fragments of sulphur adherent, condensed t there by the acids above mentioned, and which are of the same kind with that produced in such abundance in Solfatara, i But what productive cause shall we assign for those sulphureous vapours, the slow destroyers of the lava, which continually issue from a number of fissures.in Solfatara, in the form of hot white. fumes? I can conceive no principle to which they can with Greater probability be ascribed than those sulphurs of iron (pyrites) which abound at iN the bottom of the volcano, and decomposing, in consequence of a mixture with the sub- | terraneous waters, slowly inflame, cates uce those hot sulphureous vapours, which / evident prove that the subterraneous conflagration is not entirely extinguished. ‘The noisy effervescence, likewise, which in more than one place is heard under the plain of Solfatara, seems to give a certain indication of the decomposition of these sulphurs, .. _. The streams of vapour which arise from Solfatara, according to Father* Della Torre, in the night appear like flame. No person can be more competent to ascertain the truth of this fact than the abbe Breislak, who resides near the place, and who, when I ques. tioned him on the subject, assured, me that he had never obseryed. any such appearance,
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IN THE TWO SICILIES. $1
It is, however, not impossible but that, at the time he observed them, they might have undergone some change.
The vapours which arise from the ground of the Pisciarelli are very few, and almost insensible, though formerly they must have been numerous and strong, as may be in- ferred feum the great decomposition and whiteness of the lavas found there, T have already mentioned the noise with which the springs that bear this name burst from the earth, They resemble a boiling caldron. reasons assigned for this | sotsegrr sap by different authors, are various, but, hitherto, all conjectural. On applying the car to the place where the spring issues, we may perceive that the bubbling noise does not
eed from any | ce depth, but from a small distance from the surface of the earth. ere the ground here to be dug into, we might, perhaps, be able to discover this se- cret, the knowledge of which might prove advantageous to volcanic researches. want of time, and other causes, did not permit me to make the experiment myself when I was at Naples; but I entertain a hope that what I have said may induce some of the lovers of natural knowledge in that city to engage in that undertaking, which I incline to think will not be found useless.
III. We have seen that almost all the lavas of Solfatara contain within them shoerls and feltspars. But it has been proved that the changes occasioned in both the latter, by the action of sulphureous acids, are considerably less than those which take place in the lavas their matrices; which difference must arise from the nature of these two stones, which is less liable to extrinsic injuries. We find them, in fact, firmly resist the arid of the humid clements, To the south of Vesuvius, and at a little distance from Salva- tore, I have found several pieces of very acient lava, porous, and half-consumed by time, which, howev :r, preserved unaltered their black crystallised shoerls.
It has been observed that the houses of Pompeii, long since overwhelmed by Vesuvius, and now in part dug into and cleared, are found to have been built of lava. I have ascertained this fact on the spot. ‘They are of a reddish colour, very dry to the touch, and some of them will crumble under the finger, evident proofs of the change they have undergone; but no such alteration has taken place in the shoerls they contain ; they still retain the hardness and glassy splendour which is appropriate to that stone.
We likewise know that the feltspars are indestructible by the air, as appears in the porpnyries of which they are a part.
IV. I have already remaked that the lavas of Solfatara usually have for their basis the petrosilex and the horn-stone. I shall add! that I have also met with the granite in them, pee she in a large mass, but in small detached pieces, which induced me to doubt whether they properly belong to this volcano; and as they likewise appeared to me un- touched by the fire, I rather inclined to believe them adventitious. ‘This granite consists of two substatices, quartz and shoerl. thts
But another production must not be forgotten, which forms large heaps‘on one side of the internal crater of this volcano. This is an iash-coloured tufa, of a middling con- sistence, in strata of various thickness, with the superficies of ¢ach stratum covered with a'black crust, in which may be discovered manifest vestiges of plants. The abbe Breislak, . who first observed. this tufa, after having shewn it me on the spot, gave me some of these impressions of plants to examine, vey raat them to be some species of the alga marina, or sea-weed. While] was at;Naples, I had not sufficient time to make an accurate examination of them’; ‘but this! afterwards made at Pavia, from seve- ral imens of the same tufa. Some-parts exhibited only the impressions of plants, but:in others I found real leaves, They are striated, with strize running lengthwise, and when: touched with the point of a:needie, easily! :break,: and appear converted into a
——
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SPALLANZANI'S TRAVELS
carbonaceous substance, At first I doubted whether they were mae tee but on examining them again, carefully with a lens, and comparing the leaves found in the tufa with those of the natural alge, I was fully convinced they were.
This observation appeared, both to me and the abbe Breislak, to be of considerable importance ; since we may conclude from it, that part of Solfatara which is formed by this tufa, has once made a part of the bottom of the sea, and been thrown up by the action of submarine fires, Nor is it im ble that the rest of it has had the same origin, and that all the substances of this volcano have issued from the waters of the sca. Such we know to have been the origin of many other mountains, either now actu. “ burning, or which have ceased to burn.
t is well known that for a long time alum and sal-ammoniac have been extracted from this half extinguished voleano. The method employed for each was as follows. In the presess for the alum, certain square places were cleared out in el ere of Solfatara, in which it effloresced, and the efflorescences were swept together, and from them, by methods well known, the salt was collected purified. The sai-cemoniac was obtained by placing anumber of picces of tile round the apertures from which that salt issued, in the form of a subtle vapour, upon which the vapour was condensed. A description of these two methods is to be found in almost all the authors who have written on Solfa- tara; some of whom, with reason, censure them as imperfect, and consequently not likely to produce the profit which might be obtained.
ut we may now hope that both these manufactures may become objects of importance under the direction of the abbe Breislak, and the liberal patronage of Baron Don Giu- seppe Brentano, who has taken this celebrated Phlegrean field at a constant rent. The able, proceeding on the principle that the quantity of alum procured from Solfatara must be proportionate to the area of the space on which it efflorestes, instead of the nar- row squares sent 3 appropriated to this purpose, and called gardens, has greatly ex- tended the spaces allotted : and that the vg bee of this salt may not be prevented by the rain-water draining into the bottom fro: the steep sides of the volcano, he has surrounded them with small ditches, with deep wells at intervals which receive the water, and where it is soon absorbed by the spongy earth. In the lower part of these sides he has likewise opened a number of cavities equally proper to furnish alum.
The same principle appears to have guided the abbe in his attempts to increase the quantity produced of sal-ammoniac, by making use of long ®t: capacious tubes of earth, open at both extremities, and baked in the furnace. Thest seceive at their lower ends the vapours abounding with this salt, which attaches itself to their inner sides, and forms there a crust that in time increases to a considerable thickness. I have seen with pleasure at Naples the effects of these two methods; and it is expected they will be still more productive, when some alterations suggested by persoris well acquainted with this busi- ness have been made. be !
Formerly sulphur was extracted from the crater of this volcano; but the small
uantity of it, and the: low price:of the commodity, have caused ‘this labour to be
abandoned. . | ;
\ ? f sj , ‘
Descending from Solfatara, a little above the level of the sea, and near to Pozzuolo, we mect with the ruins of'g temple, supposed to have been dedicated to Serapis, and in modern times freed from’ aislimy eruption under which it was buried. » ‘This edifice may at once gratify the admirer of the imitative arts ‘by its architecture, and the curiosity of the naturalist. . Among: the s which still remain entire, are three beautiful colymns of that species of white Grecian marble, usually called cipollino. \'They are erect, but at the height of about nine feet fromthe: ground, each column begins to: appear worn;
IN THE TWO GICILIES, 53
and this wearing extending round the column, forms a horizontal band or fillet, which is rough and unequal, about two feet in breadth, while the remainder of the column {is smooth and polished. This band isin every part bored by the marine animalcule called mytilus lithophagus by Linngus, and in some of the perforations the shells are still to be found, either entire or in fragments.
But besides this species, which is well known to Conchiologists, I have discovered another, which I had before found, in a living state, in some subaqueous marbles in the lake of Venice, an accurate description of which I shall reserve for another work, Several of the shells of this mytilus, which is smaller than the other, are to be found in the per- forations of this part of the column, In fact, on oe with attention besides the holes made by the two species of mytili already mentioned, I found wee others, ex. tremely small ones, which all who are acquainted with the different species of marine animalcula, will know to be the work of other lithophagous worms. I must likewise add that I have found among them some serpules, and particularly the contortuplicata, and the triquetra of Linnwus. These are the marine animalcula which have eaten into the three columns near the middle of the shaft, — that circle of inequalities and roughness, except which there is no vestige of these animals.
n the plain of the Temple are found several other fragments of columns, some of the same cipollino marble with the former, and others of African marble ; which frag. ments have likewise bands or fillets of inequalities and roughness similar to those before described, above and below which the marble is perfectly smooth, and still retains the polish it originally received from the hand of the artist.
On the same plain we see scattered several columns of granite which appeared to me to be oriental ; the component parts of which are black mica with large flakes, which is very abundant, a large proportion of feltspar and quartz. But these columns have not been touched by the corroding worms; nor was it to be yt tt that they should, as it appease, from a variety of instances, that they only attack calcareous stone.
. Ferber, in his letters before cited, mentions this pga in the columns ; but he only notices the mytilus lithophagus, which he calls the ton. or dactylus, But the cavities in which these pholades have lodged being nine feet high above the present level of the sea, he infers that the sea has sunk nine feet, supporting this inference by the ob- servation ‘that the pholades always reside in rocks level with the surface of the water, and never are found near the bottom.”
But this is an assumption contrary to fact, as I shall easily prove. The pholades in these columns, which, according to Linnzus and other systematic naturalists, belong to the genus of the mytili, I have very frequently found in the Gulf of Spezia at Genoa, and in its environs, within the port itself of that city, in several places in the sea of Istria, and other parts of the Adriatic, and likewise in the Mediterranean, But in all these places I have found them in supaqueens rocks, never or scarcely ever level with the surface of the watcr; and frequently I have procured them to be fished up from the bottom of the sea at the depth of ten or twelve feet, by the means of long and stout forceps, which drew up large pieces of the rock in which they were contained in a living state. I have also in my possession several of these pholades, or more properly speaking mytili, infixed within the hard shells of very mage oysters fished up in 1%; presence from the depth of one hundred and forty-two feet. But in these columns we find not onl the remains of mytili, but of serpules and of other very small lithophagous worms whi are found in the. sea at every depth. As therefore the supposition of Ferber, that the pholades,.or mytili always reside at the surface of the water only is contrary to fact, his deduction that the level of the sea has sunk nine feet since the time of the corroding of
VOL. V. F
ee a =
34 SPALLANZANI’S TRAVELS
these columns, must likewise evidently be erroneous. All that we can with certainty affirm is, that the circle or fillet which has been the habitation of these marine worms, ' has been covered by the sea for a long series of years; as may be. inferred from the re- mains of these animals found in the cells they have sunk, which shew that they had attained their perfect size, to eh ee which they require nearly half a century, as I could prove by incontestible facts, did I not fear it wou'd lead me too far from my subject.
It may perhaps be objected, that it must appear extraordinary that these columns which are now in an erect position, should have been so long washed by the sea-water in that circle only, while the part of the shaft below it remained untouched. Yet might they not, before they were employed in the fabric of which they made a part, have been buried in the sea in such a manner that this circle alone, which is now rich with marine spoils, might be accessib:. to the water ?* But though this hypothesis should not ap- pear satisfactory, and I have no other to offer, I shall content myself with stating t facts of which I have knowledge, without feeling any great solicitude that I am not able to explain them.
CHAPTER III. THE GROTTA DEL CANE.
Errors of Ferber relative to this celebrated Babe ee aed # ga of the Author and abbe Breis- lak, relative to the mortiferous vapour.... Description of the grotto....Conjecture that the vapour was anciently more extensive.. .Its mean height....Its heat greater than that of the atmospii re... Consists of carbonic-acid gas, mixed with atmuspheric air and azotic gas.... This carbor:< acid, according to the abbe Breislak, is the produce of the carbure of iron contained in volcanic sub- stances, and combined with oxygene....[he mephitic vapour exhibits no signs of magnetism or electricity....Phenomena which accompanied the burning of several substances placed within the vapour....Remarks of the author on the experiments of the abbe Breislak, and his conjectures on the origin of this carbonic acid.
HAVING visited Solfatara and the surrounding rocks, continuing my journey to the west, I soon arrived at the Grotta del Cane. There is no person conversant with litera- ture who does not know that this name has been given to a small cavern between Na- ples and Pozzuolo, because if a dog be brought into it, and his nose held to the ground, he soon begins to breathe with difficulty, and loses all sense, and even life if he be not speedily removed into the open and purer air. This grotto, though so celebrated both in ancient and modern times, in fact shares its fame with several other places which are endowed with the same deleterious quality ; as it is only one of the almost innumerable pestiferous vapours in different parts of the world, especially in volcanic countries, which are quickly fatal both to brute animals and man, though they do not offer to the eye the slightest indication of their presence. They have beer, mentioned by a numerous list of writers, whom I might cite, were I disposed to may.< an unseasonable parade of my reading. It is to be remarked that the greater part of these vapours are only tempo- rary, wheceas that of the Grotta del Cane is perpetual, and seems to have produced its deadly effects in the time of Pliny. A man standing erect suffers nothing from it, asthe mephitic vapour rises only to a small height from the ground: I therefore entered it without danger; but notwithstanding the most attentive observation I could make, I could not perceive the smallest visible exhalation. :
* They may have originally belonged to an edifice ina dictant country, overwhelmed by the eea.
h certainty
e columns ea-water in Yet might , have been vith marine uid not ap- stating t am not able
d abbe Breis- lat the vapour AtMOSPiIt Teseee carbor.:< acid, volcanic sub- magnetism or ed within the is conjectures
ourney to the t with litera- between Na- > the ground,
if he be not ebrated both es which are innumerable ntries, which er to the eye a numerous parade of my only tempo- produced its om it, as the bre. entered it uld make, I
it by the oe
IN THE TWO SICILIES. 35
It therefore appeared to me that M. Feroer must have been mistaken, when he says, “‘ the killing damps rise from the ground about a palm above the floor, move along it as a white smoke, and spread through the door in the open air.”* But as it has already been observed nat the s:noke of a torch extinguished in the vapour sinks downwards, assumes a whitish colour, and goes out at the bottom of the door; it appears probable that this occasioned his mistake, especially as he mentions the experiment of the extin- guished torch in the same place.
As little can I agree with him that the mischievous effects of this vapour are the con- sequence of the air being deprived of its elasticity ;+ since it has been demonstrated that they are to be attributed to the carbonic-acid gas; as was first proved hw ‘is learn- ed countryman, M. Adolphus Murray. As we know likewise, that a canule seing ex- tinguished in this gas, the fumes which proceed from it mix more readily with the gas than with the atmospheric air ; we perceive why the smoke of a torch that ceases to burn in the Grotta del Cane sinks where the pestiferous vapour is strongest, and passing along the ground, goes out at the lower part of the door.
e person who is the keeper or guide at the grotto, and who shews to strangers the experiment of the dog for a gratuity, when the animal is panting and half dead, takes him into the open air, and afterwards throws him into the Relatihousing lake of Agna- no; a cana | that this short immersion into the water is necessary completely to re- store him. . Ferber relates this fact, and shews that he believed all that was told him concerning it. The truth however is, that the plunging the dog into the lake isa mere trick to render the experiment more specious, and obtain money from the credu- lous, as the atmospheric air alone is sufficient to restore the animal to life.
The experiments made by M. Murray, to ascertain the nature of this mephitic va- pour, have discovered to us what was before unknown, and we owe to him every grate- ful acknowledgment. They have not however explained every thing we could wish to learn relative to this cavern. Whoever is versed in the knowledge of nature, and acquainted in any degree with the dificult art of making experiments, must be con- vinced what a number of these might be made in it, which would greatly tend to throw new light on physiology and physics. I conceived a strong desire to attempt several, and communicated my intention to the abbe Breislak, who accompanied me to the Grotta del Cane. We agreed to divide them between us, that I should apply myself ic the physiological, or those which had for their object living beings, and he bestowed his attention on thé physical. As I was on the point of setting out for Sicily, I resolv- ed to carry this plan into execution on my return to Naples. But Mount Etna and the Lipari isles detained me a long time ; and when I returned I had scarcely time to visit Vesuvius, being obliged to repair almost immediately to Padua, to begin my public lectures in Natural History. My friend the abbe, however, who resides constantly near Solfatara, in consequence of his superintendance of the works there, proceeded after my
‘departure to fulfil the task I had ary him, and communicated to me the result of his i
experiments in a letter, which with his consent I here publish, as I am convinced that it will be highly gratifying to my readers. :
vi Resvkecasiz FRIEND, ; Naples, Nov, 20, 1790. . “WHEN you visited this city two years ago, to make observations on the Phlegrean fields, you did me the honour to propose to me to assist you in making a regular series * Forber’s Travela,through Italy, p.. 146 of the English translation t Ferber’s Travels. F 2
=
eae
56 SPALLANZANI’S TRAVELS
of experiments on the celebrated mephitic vapour of the Grotta del Cane. You may remember that we agreed to divide between us the objects to beexamined. You pro- posed to inquire in what manner the exhalation acts on the animal ceconomy, soas first to suspend its functions, and at last totally destroy them, unless the means of restoration are speedily applied. This problem, thougtr considered by many, has never been in- vestigated with that precision and accuracy which it deserves, nor have experiments been sufficiently multiplied and diversified to establish a general rule. From you I expected that it would have received new light, accustomed as you are to develope the most com- plicated arcana of nature. In the experiments to be made, you reserved to yourself the physiological, leaving to me the physico-chemical. Your journey into Sicily, and your
ty return to Padua to exercise the duties of your professorship, rendered it impossible at that time for you to execute your part of the plan. I have not dared to treat a sub- ject reserved for you, but I hope that some other, to me fortunate, combination of cir- cumstances may once more bring you back to Naples, and afford you an opportunity ta prosecute these inquiries, together with others analogous to them. In the mean tir’, in some excursions which I have made to the lake Agnano, I have examined with the utmost attention, this little grotto; and have made several experiments, by the detail of which I doubt not but you will be gratified. The subject it is true, has been repeatedly examined by many naturalists, both natives of Italy and foreigners ; but their success has not been sufficient to preclude every new experiment.
“The mephitic vapour, as you well know, occupies the floor ofa small grotto near the lake Agnano, a place highly interesting to naturalists from the phenomena its environs present, and the hills within which it isincluded. This grotto is situated on the south- east side of the lake, ata little distance from it. Its length is about twelve feet, and its breadth from four to five. It appears to have been originally « small excavation, made for the purpose of obtaining puzzolana. In the sides of the grotto, among the earthy volcanic matters are found pieces of lava of the same kind with those we meet with scat- tered near the lake. Iexamined some of them, and found them a compact lava, of a deep gray colour, interspersed with small hexadreous prisms of mica. ‘They are of an eeythy grain, a micaceous consistence, and have a sensible effect on the magnet. Par- ticles of feltspar are rarely found in them, and we meet with no specimens which contain shoerls, Iam persuaded that were new excavations made in the vicinity of the grotto, at a level with its floor, or a little lower, the same ct ae vapour would be found, and it would certainly be curious to ascertain the limits of itsextent. It would likewise be extremely advantageous for physical observations were the grotto somewhat enlarged, and its floor reduced to a level horizontal plain, by lowering it ‘two or three feet, and surrounding it by a low wall, with steps at the entrance. In its present state, it is ex. tremely inconvenient for experiments, and the inclination of the ground towards the dz causes a great part of the ra from the effect of its specific gravity, to make its way out close to the ground. hen I consider the narrow limits of this place, and the small quantity of the vapour which has rendered it so celebrated, I have no doubt but it must have undergone considerable changes ; for it does not appear probable to me. that Pliny meant only the present confined vapour, when (lib. ii. cap. 93.) enumerating many places from which a’ ly air exhaled, he mentions the territory of Pozzuolo. The internal fermentations by which it is caused are certainly much diminished im the vicinity ofthe lake Agnano. ‘The water near its banks is no longer seen to bubble up, from the disengagement of a gas, as we learn that it formerly did, from accounts of no very great antiquity, ..1 have attentively examined the borders of the lake when its waters were at the highest, and after heavy rains, but I sever could discover a single bubble of air. A
he grotto und, and
ubt but it ome that ing man’
lon The € vicinity , from the very great rs were at fair. A
» myself on the principles laid down by Dr. Craw
IN THE TWO SICILIES. 37
number of aquatic insects which sport on the surface, muy at first view occasion some deception; but a little observation will detect the error. If we do not suppose those au- thors who have described the ebullition of the water near the banks of the lake Agnano to have been deceived, we must at least confess that this phenomenon has now ceased. The quantity of the hepatic vapours which rise in the contiguous stoves, called the stoves of St. Germano, must likewise be greatly diminished from what it anciently was: for adjoining to the present stoves, we still find the remains of a spacious ancient fabric, with tubes of terra cotta inserted in the walls, which by their direction shew for what purpose they were intended. It appears certain that this was a building in which by the means of pipes properly disposed, the vapours of the place were introduced into differ- ent rooms, for the use of patients, who were accommodated there in a much better man- ner than they are in the modern stoves of St. Germano, which wretched places nothing could induce them to endure but the hope of being restored to health. ‘To these ruins, however, the vapours no longer extend; so that if this edifice still remained, it could not be employed for the purpose for which it was intended. The veins of pyrites which have produced the more ancient conflagrations of the Phlegrcan fields, between’ Naples and Cuma, and which in some places are entirely consumed, approach their total ex- Spstien But let us proceed to the experiments made, and frequently repeated within
e tto.
“TT. The first had for its object to determine the height of the mephitis at the centre of the grotto, that is, at the intersection of the line of its greatest length with that of its
_ greatest breadth. This height varies according to the different dispositions and tempe-
ratures of the atmosphere, the diversity of winds, and the accidental variations that take place in the internal fermentations by which the vapour is produced ; it may however be estimated at a mean, at eight Paris inches.
‘II, The entrance into the mephitis is accompanied with a slight sensation of heat, in the feet and lower part of the legs. When, in the year 1786, T visited the large me- phitic vapours of Latera, in the dutchy of Castro, I likewise observed that they produced the sensation of heat in the part of the body which was encompassed by the mephitic atmosphere, Yet on taking out of the vapour sever:'l substances which had remained in it a long time, as stones, leaves, carcasses of animals, &c. I found that these were of the same temperature with the atmospheric air; but as I hud broken my thermometer on the;road, and was unable to procure another in any of the places through which I passed,
I,could not ascertain the temperature of the mephitis. I felt in my body a slight degree
of heat, which I could not perceive in the substances I took out of the mephitic vapour; ee endeavouring to compare one thing with another, I concluded that the témperature of
e mephitis was the same with that of t afi oa air, which I attempted to explain to ord. Buta number of other experiments made in the Grotta del Cane, convinced me that this exhalation has a distinct degree of heat different from that of the atmosphere. In these experiments, which I repeated many times, the the. mometer suspended at the aperture of the grotto, three feet above'the sur- face of the mephitis, stood at between 13 and 14 of Reaumur’s scale (62 and 64/of Fahr.) and _ placing the ball on the ground, so that it was immersed in the mephitic vapour, the mercury arose to between 21 and 22 of Reaumur (80 and 82 of Fah.) or ought
_ It to excite surprise, that the substances taken out of the mephitis did not exhibit this diversity of temperature, both because the difference’ is small, and ‘on acedunt of the
quantity of humidity with which they are always loaded, and which produces‘on their
» Surface a.continual evaporation. _I frequently repeated this experiment, making use of
rent, thermometers, because I knew that the celebrated M. Adolphus Murray when
$8 SPALLANZANI’S TRAVELS
he made his experiments in the Grotta del Cane, had noi observed the vapour to pro- duce any effect on the mercury in the thermometer.
‘III, I repeated, for my own satisfaction, the usual experiments made by many natu- ralists, with the tincture of turnsole, lime-water, the crystallizations cf alkalis, the ab- sorption of water, and the acidulous taste communicated toit, which prove beyond all doubt the existence of fixed air, or carbonic acid, in the exhalation of which we treat. But is it composed of fixed air alone? This I wished to ascertain, When exposed ina cudiometer to nitrous gas, an absorption took place, to about the ys of the quantity, In a phial filled with this air, and continued with the mouth immersed in water for fif- teen days, the water slowly rose until it occupied 7: it may therefore be concluded, that the relative quantities of the different gases which compose the mephitic air of the Grotta del Cane are as follows: vos of \iial air, or oxygenous gas, 7% of fixed air, or carbonic acid, and 75 of phlogisticated + azotic gas; or perhaps it is a mixture of carbonic acid and atmospheric air, with; all quantity of azotic gas, more than is contained in the atmospheric air.
‘‘ The vicinity of the grotto to the stoves of Agnano, the warm vapours of which con- tain a considerable quantity of hydrogenous sulphurated gas, induced me to suspect that some portion of the latter might be found mixed with the gas of the mephitis; but I was not able to discover in it the smallest quantity. I made use. of the sugar of lead, or acetite of lead, which, as you well know, is extremely sensible to the slightest impres- sion of hepatic gas, leaving it immersed in the mephitis for the space of half an hour.
“It is certainly a curious problem to investigate the origin of this fixed air. You are acquainted with the different opinions of naturalists, some of whom consider it as an at- mospheric air changed into fixed by the action of the electric matter of the lava; while others suppose it produced by a slow and successive decomposition of the calcareous earth, effected either by a subterraneous fire, or by an acid. But the fact is, that 'n the Grotta del Cane there is nota single vein of lava, and that the atmosphere of that vici- nity exhibits no particular signs of electricity. The hypothesis founded on the decom- position of the calcareous earth, is likewise subject to great difficulties. Our excellent common friend, the Commendatory de Dolomieu, in his valuable notes to the disserta- tions of Bergman on the products of volcanos, is of opinion that the fixed air of volcanic places is produced by the re-action of the sulphur on the calcareous earth, with which it forms a liver ofearthy sulphur. I am rather inclined to believe that the fixed air of vol- canized countries is not developed ready formed from any substance, but is the produce of the plumbago contained in the iron, with which all volcanic substances abound com- bined with the base of vital air afforded by the internal decompositions of the pyrites, Tam noi induced to embrace this system by its novelty. The experiments of Messrs, Lavoisier, Berthollet, Mongez, Landriani, and many other excellent chemists, com- pared with local observations, have proved, beyond a doubt, the existerce of plumba. go in iron. It is certain that all volcanic substances abound in iron, and the hepatic vapours which rise in the stoves of St. Germano, in the vicinity of the Grotta del Cane, prove the internal decomposition of the pyrites, which still takes place here : adecom- position which, by giving birth to the mephitic acid, furnishes likewise the base of vital air. :
““ STV. Among the notices which the celebrated Bergman wished to receive, relative to the Grotta del Cane, he desired a detail of the phenomena of magnetism and electricity. With respect to the former, I have observed no new appearance. The magnetic needle, placed on the ground, and consequently immersed in the mephutis, rested in the direc- tion of its meridian; and, at the approach ‘of a magnetized bar, exhibited the usuab
IN THE TWO SICILIES. 39
effects of attraction and repulsion, according as cither pole was presented. With re- gard to the latter article, it is not possible to make electrical experiments within the mephitis ; not because that kind ofair is a conductor of the electric fluid, as M. Murray imagined, but because the humidity that constantly accompanies it disperses the electric matter, whi 1 not being collected in a conductor, cannot be rendered sensible. I several times attempted to fire inflammable gas, in the mephitic vapour, with electric sparks, by
: means of the conductor of the electrophorous; but, notwithstanding my utmost endea- vours to animate the electricity, I never could obtain a single spark ; as the isolator (a became a conductor the moment it entered into the mephitis, on account of the humi-
dity which adhered to its surface.
< “'V. One of the pencips objects of the researches of academies and naturalists at pre- sent is the theory of the combustion of bodies. My first experiment was directed to
ascertain whether those spontaneous inflammations which result from the mixture of
rf concentrated acids with essential oils could be obtained. I placed on the round, in the grotto, a small vessel, in such a situation that the mephitis rose six inches above the M edges of the vessel. I made use of oil of turpentine, and the vitriolic and nitrous acids, at and the same inflammation followed, accompanied with a lively flame, as would have I taken place in the open atmospheric air. The dense smoke which always accompanies Sp these inflammations, attracted by the humidity of the ad gar presented its undulations r to the eye, and formed a very pleasing object. As I had put aconsiderable quantity of J acid in the vessel, I repeatedly poured in a little of the oil, and the flame appeared in ha the mouth of che vessel fifteen times successively. This oxygenous principle contained ts in the acids, and with which the nitrous acid principally abounds, undcubtedly contri- le buted to the production and duration of this flame, though enveloped in an atmosphere is inimical to inlummiation. a ** In the district of Latera, which I have mentioned above, I observed that in a mephitis i. of hydrogenous sulphurated gus, or hepatic gas, a slow combustion of phosphorus took " place, with the same resplendence as in the atmospheric air. As I had not with me a nt sufficient quantity of phosphorus, I could not proceed farther with this experiment, nor 4s vary it as might have been necessary. In the mephitis of Agnano, the first experiment c I made was with common phosphoric matches, of which I broke five, holding them it close to the ground, and consequently immersed in the mephitis. They all produced a 1. short and transient flame, which became extinguished the moment it was communicated 4 ‘to the wick of a candle. ‘The second experiment I made was the following; I placed . on the ground, in the grotto, a long table, in such a manner that one end. of it was : without the mephitis; while the other, and four-fifths of its whole length, were im: iy mersed in it. Along this table I laid a train of gunpowder, beginning from the end Ha without the hay gst and at the other, which was immersed within it, the depth of v seven inches, I placed, adjoining to the gunpowder, a cylinder of phosphorus, eight " lines inlength. The gunpowder without the mephitis being fired, the combustion was = soon communicated to the other‘extremity of the train, and to the phosphorus, which # took fire with decrepitation, burnt rapidly, with a bright flame, slightly coloured with
of ellow and green, and left on the wood a black mark,.as of charcoal. ‘The combustion ted nearly two minutes, till the whole phosphoric matter was consumed. -. “T then proceeded to.another experiment. | I placed some gunpowder on the ground
Wf in, the grotto; and having lighted q cylinder of phosphorus without the mephitis, I im- « merged it within it while burning, carried it the distance of ten feet, and threw it on.the 3 gunpowder, which immediately took fire. No alteration ws perceptible in the flame, a ; or manner of burning, of the lighted phosphorus, either at the moment of its entrance
into the mephitis, or during its continuance in it.
40 SPALLANZANI’S TRAVELS
“T afterwards lighted another cylinder of phosphorus, and conveyed it immediately into the mephitis, supporting it with a small piece of wood; and this likewise burnt briskly, until it was entirely consumed.
“It may perhaps be suspected that, in the experiments with gunpowder, the oxygenous gas contained in the nitre co-operated to the combustion of the phosphorus; but it is certain that, independent of the nitre, this curious substance, though it burnt in me. phitic air, presented the same appearances as in the atmospheric air. I am aware that, among the experiments of M. Lavoisier, there is one on the combustion of phosphorus
roduced by means of a burning mirror, under a glass bell, the mouth of which was immersed in mercury. That excellent naturalist observed that the phosphorus began to burn, but that in a few moments the air of the receiver being no longer proper to nourish the combustion, it became extinguished. _Is it not probable that the extinction of the phosphorus did not proceed from the infection of the air, but that the vapours of the phosphoric matter remaining confined in the receiver, and condensing around the phosphorus, suffocated its flame? The mephitic gas of the Grotta del Cane is cer- tainly unfit for the respiration of animals, and the inflammation of common combustible pl ia but phosphorus, nevertheless, burus in it, and emits, as usual, luminous sparks, me I must not conclude without noticing the production of the phosphoric acid from the slow combustion of phosphorus in the mephitis. Perhaps this may present particular modifications, dependent on the carbonic acid, to which it must necessarily unite itself in this situation, But I have not yet been able to prosecute this experiment, the tem- perature of the place not being such as is requisite to make use of the apparatus suited tothe method of M. Sage. I shall therefore defer the investigation of this subject until the winter, when I purpose to resume it, if I can procure free access to the grotto, for some little time, by satisfying the avidity of iis rapacious guardian. I remain, with sentiments of the utmost friendship and esteem, Your devoted servant and friend, Scipio Breisiak.”
The observations and experiments communicated in the above letter, undoubtedly enlarge very considerably the sphere of our knov. ‘edge relative to this mephue place ; and I sincerely congratulate the author on the success of his researches. But the same sincerity induces me to mention an observation which occurred to me while reading his letter, and which I am convinced his friendship will permit me to make public. The method he used to obtain the mortiferous gas on which he made the experiments here related, was, I doubt not, the same with that employed to ascertain the salubrity of the atmospheric air ; that is, by taking a phial filled with water, inverting and plunging it into the mephitis, then letting the water gradually out, and carefully closing the phial. Had any other method been used, I doubt not but it would have been mentioned. But by this the mephitis could not be obtained pure, such as it immediately issues from the floor of the grotto, but must be more or less mixed with atmospheric air. For the carbonic acid gas being heavier than the atmospheric air, it must consequently form a stratum in the lower parts of the grotto, where it will in general remain, though. there will be some mixture of the two fluids; especially when the door is opened, and the internal am- bient air put in motion. Hence the mixture of the three gases, the carbonic acid, the azotic, and the oxygenous obtained by the abbe Breislak. I had, however, suggested to him, that the best method to obtain this emanation pure would be to dig a small trench in the ground of the grotto, and to fill it with water; when a number of bubbles
IN THE TWO SICILIES. 41
would no doubt rise from the bottom to the surface, which would probably only consist of the carbonic acid gas suspended in the body of the water, ‘The contents of these bubbles might be collected by methods well known, and we should thus procure the genuine mephitis, without any mixture of atmospheric air, For greater accuracy in the experiment, mercury might be placed under the water; as it seems probable that the tufaceous soil would not be sufficiently dense to retain it.
We have seen the opinion of this learned naturalist, relative to the origin of the car- bonic acid in this grotto. It is evident that in this, as in many other questions of a si- milar kind, we can only amuse ourselves with conjecture, and perhaps we may never be . able to proceed farther than conjecture, relative to an operation which nature has veiled in profound obscurity, and withdrawn from the observation of our senses. But since certainty is not attainable, I must ingenuously declare, that among the different hypo- theses that have been framed to account for this abstruse phenomenon, I prefer that which supposes that the mephitis of the Grotta del Cane is separated, by the means of fire, from carbonatcs of lime (or calcareous earths) and that, passing through different volcanic substances, it has penetrated to that place. It is highly probable that the vol- canos of the Neapolitan territory, and also those of the ecclesiastical state, are superin- cumbent on strata of such carbonates, continued and connected with those of the Apen- nines. In my way from Lombardy to Naples, when I arrived in the neighbourhoc:1 of Loretto, the road began to lead between mountains, which continued to Fuligno, a dis- tance of nearly seventy miles. ‘These mountains, almost all with horizontal strata, are composed of these carbonates. ‘The road from Fuligno to Spoleto and Terni presents a chain of mountains of the same kind, and nearly with the same stratifications. These mountains extended to within a little distance of Civita Castellana, where I found suffi- cient testimonies of extinct volcanos, in the puzzolano and lavas, which I met with at every step. Some of these lavas are of a base of shoerl in the mass, and others of a horn- stone base: they all resemble the Vesuvian with respect to the white garnets they contain. The volcanic bodies, and various kinds of tufa and puzzolana, continued to present themselves quite to the gatesof Rome. From this city, continuing my journey to Na- ples by the way of Veletri, I continually met with volcanized matters; but at Terracina the mountains next the sea again appeared to be formed of calcareous earth, as did those of Sessa. But whatever may be the character of the more elevated parts, the bottoms, through which the high road passes, consists of tufa, which exhibits the true signs of volcanization not only in the pieces of lava, and the great number of pumices it contains, but from being in a great degree a mixture of small fragments of lava and scoria.
It is to be remarked, and it is worthy of attentive consideration, that when we leave the road, and ascend the steep eminences on its sides, we frequently find beneath the tufa calcareous stone, especially in places where the former has been corroded by rain water. The remainder of the Apennines from Sessa to Naples are formed of the same ie stone; though in lower situations the volcanic tufa is scarcely ever inter- rupte
In Chap. VI, I shall speak of a volcano which I observed near Caserta, a small city about sixteen miles from Naples. I shall then shew that the volcanic matters are there every where surrounded by calcareous stone.
The Fossa Grande, which descends laterally from Mount Vesuvius, and which I have mentioned in Chap. I, is bordered on the sides by two high rocks. That which is on the left, the side toward Naples, owes its origin to an aggregate of lava; while that on the right is composed of pumice stone and tufa; which not being firmly connected,
VOL. Vv. G
Rese eS eee
42 SPALLANZANI’S TRAVELS
frequently fall by their own weight, especially when loosened by rains, and in their fall bring down with them various substances, of which some are calcareous spars, mixed with pieces of the common calcarcous earth, which, as I have already mentioned, I met with in my journey to Naples. ‘These substances seldom exhibit any traces of injury by the fire: their angles likewise are not blunt or ragged, but sharp. It is, however, indubitable that they are pieces rent from great masses of calcareous stone, before the vehemence of the fire had time to change them. These observations I made on my return from Vesuvius to Naples.
‘The author of the Campi Phlegrei, speaking incidentally of the Fosse Grande, gives the figure of a piece of calcareous breccia found there ; and observes that similar pieces are frequently found in the excavations made by the rains in the sides of Vesuvius and Monte Somma. ‘The Lithologia Gioeniana, which treats on the productions of this volcano, mentions similar calcareous stones to have been thrown up from its mouths in former times.
The island of Capri, near Naples, it is to be observed, is likewise composed of cal- careous earth.
From all these observations, ‘it appears to admit of no doubt that the Neapolitan ter- ritory, which we see volcanized, rests on calcareous strata. This was likewise the opi- nion of Ferber and Sir William Hamilton.
If then we suppose the subterrancous fire to act gradually on the calcareous stone, compelling it to divest itself by degrees of its acid, while it becomes covered with earthy aggregations casily permeable to this acid, now becomes gaseous, the gas will issue above it, and fornia current mingling with the atmospheric air. This probably will ex- plain the nature of the emanation.in the Grotta del Cane. The abbe Breislak has shewn that the heat of this emanation is greater than that of the atmosphere ; which affords us reason to suppose that a remainder of volcanic fire exists under the grotto. ‘The great humidity of the vapour is likewise extremely favourable to this hypothesis, since we know that calcareous stone, by the action of fire, is not only deprived of its acid, but of the water which it contained. It may be objected that on this supposition the mephi- tis must diminish; but it should be considered that its extent is very confined, while the quantity of the subjacent calcareous matter is immense ; and it is likewise well known what a prodigious quantity of this acid is combined with such stones.
This hypothesis will likewise explain the temporary mephites which arise only in consequence of particular eruptions, as frequently happens in the environs of Vesuvius. The deleterious exhalations will continue till the subterrancous fires have decomposed the calcareous stones ; but they cease when the conflagrations are extinguished.
IN THE TWO SICILIES. 4S
CHAPTER IV.
SAKES OF AGNANO AND AVERNO.,.MONTE NUOVO...PROMONTORY AND CA. VERN OF MISENO...ROCK OF BURNT STONES....PROCIDA.
The lake of Agnano once a spacious volcanic crater....Tenches and frogs found in this lake... The absurd report that monstrous animals are produced there, detected by Vallisneri....The lake of Averno presents the mouth of another ancient volcano....[t is false that birds cannot approach this lake....No deleterious exhalation emitted by it... Volcanic substances of Montc
uovo....L.avas found there of the nature of pumice and enamel....Soda grows in a little cavern of its crater....Peculiarity of amphibious animals observed here....The cavern of Miseno abounds in sulphate of alumine (alum) and pumice....Well of water full of gaseous bubbles... Volcanic crater still discernible on the promontory of Miseno....Pumices found there, contain- ing feltspars....Lava, pumices, and enamels of the same nature, found on the Rock of Burnt Stones, and at Procida....Great friability of this enamel, not common to volcanic enamels, and its probable cause.
THOUGH the Phlegrean fields are numerous, I in this work propose to describe, or at least to give a sketch of them all; since, though they are all volcanic, the objects they present are few, and little different from each other.
believe no one doubts that the cavity filled with water, and usually denominated the lake of Agnano, has been the mouth of a volcano. It certainly has internally the re- semblance of one, since it is shaped like an inverted funnel, the usual figure of vol- canic craters. It must have been a very large one, since it is nearly two miles in circuit. Numerous flocks of ducks swim on its surface, and its waters contain great quantities of tenches and frogs, which were once celebrated for a pretended monstrous formation, until the cause of this absurd error was detected by Villisneri. It may not perhaps be uninstructive should I, by way of an amusing digression, relate the story of this plea- sant mistake to the reader.
It is well known that frogs, before they arrive at the perfect form of their species, have that of a kind of worms, usually called tadpoles, the bodies of which are of an orbicular shape, and have tails. We know likewise that these tadpoles become frogs by degrees, the hinder legs being first produced, and afterwards the fore legs, while they retain the tail for a considerable time. This gives them a strange appearance, as the tail peer like the lower half of a fish, while the round body and legs resemble the frog. Hence persons unacquainted with the productions of nature have supposed them to be monstrous animals, half fish and half frogs. A credulous Neapolitan brought one of these monsters, which he said wasa native of the lake Agnano, to Villisneri, at Mi- lan, that he might view it and admire. It did not, however, require the knowledge of so great a naturalist immediately to perceive the absurd error. The tadpole, which to him was an ovject of laughter, not of admiration, was of an extraordinary size, whence he concluded that the frogs of the lake Agnano were extremely large. They are not, however, larger than the comn 10 size, nor did I find thc tadpoles bigger, though, as it was the end of July, they had arvived at their full growth, and many, having cast their tails, had become perfect frogs. ‘That which was shewn to Vallisneri was possibly brought from some other country, perhaps America, where the frogs grow to an ex- tremely large size.
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A4 SPALLANZANI’S TRAVELS
The sides and bottom of this lake are of tufa, interspersed in some places with frag. ments of lava and pumice-stone; though we do not find, at least so far as the eye can reach, any veins or strata of lava: whence I infer the eruption to have been entirely, or in a great degree, thick and pan
Te eame ideas which naturally occur to the observer at sight of the lake Agnano, will be suggested likewise by that of Averno, as there can be no doubt but this likewise was the crater of an ancient volcano, The Greeks called it Aornus ; because no birds were found near it, probably on account of some pestilential vapour which then exhaled, and deprived them of life. ‘The author of the Campi Phlegrai asserts that it is very rarely that any water-fowl are to be seen on this lake, and that when they come they re. main there but a very short time. The truth however is, that whenever I was there, I saw great numbers of teal swimming on the surface, and the peasants assured me that the lake abounded with water-fowl in the winter. Nor do I know any cause which can, at present, drive them from a pues where they may find plenty of food ; as neither the environs, nor the lake itself, afford any indications of noxious exhala- tions.
These two places lie to the west of Naples, near Pozzuolo, in the vicinity of which is Monte Nuovo, so called because it was produced by subterranean fires in 1538, It is not very high, and seen from the port of Pozzuolo, appears to be an obtuse cone ; but, on reaching the top, we discover that this cone is oni the exterior part of a cra- ter, the upper edges of which form a circle of about one hundred and fifty feet in diameter.
Like other volcanic craters, the internal sides of this grow narrow towards the bottom, and both that which I call the bottom, and the external part of Monte Nuovo, consist of a friable tufa, in many places, covered with plants. The sea bathes the sides of this volcano, which, if they are dug into a little, as well within the water as without, are found very warm. The same warmth is likewise perceived at the bottom of the crater. From such excavations, likewise, arise thin warm vapours. In fact, in the internal parts of Monte Nuovo we find all the last remains of volcanic conflagration.
In the external sides of the mountain many pieces of lava are found, which deserve notice from their singular quality. They are a substance of a middle character between lava and pumice-stone, on which account I shall call them pumice-lavas. They have the lightness and friability of a compact pumice-stone. When broken by the teeth, by which a good judgment may be formed of some stones, they appear real pumice-stone. They are dry and rough to the touch, as is usual with such kinds of volcanic produc- tions. Their structure is not fibrous, contrary to what we observe in common pumice- stone, but granulous, and very similar to that of various kinds of lava, as is likewise the internal appearance. This production is of importance, as presenting a middle sub- stance between lava and pumice-stone. The base of these stones is a horn-stone, mix- ed with a few feltspar scales: they scarcely adhere to the tongue, and emit a slight argilla- ceous odour. In the furnace they produce a compact enamel, of a dark gray colour, transparent at the angles, and which gives a few sparks with steel,
Towards the internal bottom of the crater we find, projecting from the tufa, the same kind of lava, penetrated with feltspars, but more compact and heavy, and interspersed with beautiful and shining veins of black enamel of various thickness. I am in doubt whether this species of vitrification was the consequence of a greater degree of heat to which the lava had been there exposed, or whether, from the difference of its quality in those places, it had undergone a more perfect fusion, and become enamel, while in others it had remained in the state of lava.
IN THR TWO GICILIES, AS
On the side of this bottom we find, within the tufa, a small cavity, | know not whether formed by nature or art, that abounds with saline efllorescences, which I at first imagined to be muriate of ammoniac (sal ammoniac) or sulphate of alumine (alum) but their urinous acrid taste, the green colour which they gave to syrup of violets, and other qualities that are proper to soda, and which I omit for the sake of brevity, leave no doubt that they are formed from that salt. Besides these efflorescences, the small ik corners, and bottom of this cavity are more or less covered with the dust of this soda.
I cannot take leave of this volcano without mentioning an observation, which has some analogy to what has been before noticed of lake Agnano, as it relates to the same species of animals. On the tufaceous sides of the crater, both internal and external, as often as I approached them, I sawa great number of frogs leaping about. They were nearly half an inch long, and a quarter in breadth. ‘They had the complete form of the frog, were of a dark yellow colour, and their fore feet were divided into four toes, and their hinder into five, though they have not the shape of the hand, which constitutes an essential difference between these frogs and the others of these countries. But how are these amphibious animals produced ? Among all the different species of European frogs (and under this genus I, with Linnzus, likewise include toads) I know none which do not begin their existence in water, and continue to live in it some time, until they throw off the mask of the tadpole, and assume the shape of frogs. But Monte Nuovo is not only entirely without moisture, but, as I learned from the peasants who reside in the nelahibcusbend, even when heavy rains fall, the bottom of the crater (which is the only place where rain-water can be collected and retained) imbibes all the water immediately ; as, in fact, it must, since it consists of a light spongy tufa full of cracks and fissures.
The only water near, is that of the lake Agnano, about half a mile distant ; from which these animals might he supposed to have derived their origin, were it not that the frogs of that lake are of a totally different species. I must therefore confess, that the presence of these creatures here was to me an enigma, which, perhaps, I might have been able to have solved, not without some advantage to natural knowledge, had I been able to have made a longer stay in this volcanic country.
Before we reach the promontory of Miseno we arrive at the harbour, which is a very secure basin, as it is surrounded on every side by eminences. This was the port for the Roman fleet in the Mediterranean. ‘The eminences are of tufa; and, on one side, a little above the level of the sea, we find a spacious cavity, the work of art, called the Cavern of Miseno, in which the m ariate of alumine continually efforesces. This salt is either unknown to or neglected by the inhabitants ; though it might be extracted with great advantage, especially were the cavern enlarged (which it might easily be, as the tufa is extremely soft) since the saline efflorescences would certainly increase in propor-
‘tion to the enlargement of the superficies.
At the bottom of the cavern there is a well of water bubbling up, with sometimes more, sometimes fewer, gaseous bubbles, which rise from the bottom. The water is nearly of the same temperature with the atmosphere, and the gas, from the scent, ap- pears to be sulphurated hydrogenous ; but I had not convenient opportunity exactly to ascertain its quality. The sides and roof of the cavern are scattered over with conamon pumices, containing various feltspars, some calcined and consequently deprived of their me lustre, without, however, having lost their natural crystallization, which is thomboidal.
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46 SPALLANZANI'S TRAVELS
Beyond the port of Miseno is the promontory of the same name, which forms a tufa- ceous mountain of no despicable height ; from the top of which some admirable prospects resent themselves, ‘T’his, likewise, certainly owes its origin toa volcano, as its crater is still very discernible, though in a great measure destroyed, on the south side, by the waves of the sea,
Having proceeded to some distance from this promontory, I met with several lavas immersed in the tufa, both of the compact and porous species, but common to other vol- canos, and all detached. Mixed with these were various pieces of pumice, in like man- ner detached, in which feltspars were, I will not say scattered, but thickly sown. Ina square inch of this pumice I counted fourteen on the exterior surface, and forty-seven within, ‘They are crystallized with various faces, are somewhat less hard than quartz, and have that changeable brilliancy which is inseparable from feltspars. The fire does not appear to have been able to injure them, though it has changed their base into pu- mice, which is in fact a real vitrification.
In front of Procida, and at a little distance from it a small low rock projects into the sea, formerly only known to fishermen, and called the Rock of Burnt Stones, because it is in fact a mixture of pumices, enamels, and lavas. ‘The first naturalist who noticed it was the abbe Breislak, who conducted me to it witha particular kind of pleasure, as a place (epee to himself. A stay of two hours, which I made on it, was well rewarded by the objects it presented. Its elevation above the surface of the water is only a few feet, and consequently in tempestuous weather, it must be covered by the waves. On making the circuit of it in a boat, and examining it, we find that only the
rojecting points rise above the water, and that the body of the re zk is below the surface. Hence it appears probable, that it was once much larger, but has been in a great degree destroyed by the violence of the waves.
‘The stones of which this rock is composed are principally of two qualities, The first, a lava of a horn-stone base, light, of a dark gray colour, an earthy grain, unequal, »nd which gives scarcely any sparks with steel. Th. second is a lava, with a base of shverls in the mass, which has ee various changes and modifications, according to the different heats to which it has been exposed. In many fragments, therefore, we onl find it a simple lava, while in others, it has become pumice, and in others enamel. In one part they appear of a witish colour, fibrous, light, and extremely friable ; but, as their levity and friability diminish, they become more compact, and the fibres less discernible ; the colour grows darker, and a glassy lustre begins to appear. A little far- ther, their fibrous quality is entirely lost;. their compactness, weight, hardness, and lustre increase, and the unequivocal characters of a perfect enamel are seen. ‘This ..tter is black, gives sparks with steel, and in its appearance resembles the iy fag Its black colour is interrupted by feltspars, which are likewise common to the first lava with the horn-stone base. They are extremely brilliant, somewhat fibrous, crystallized in hexaedrous prisms, and several of them five lines in length.
It frequently happens, that the volcanic productions which exist in one place are found likewise in another: that is, that in different situations the earthy matters and the activity of the fire have been the same; a concurrence which may easily take place in various parts of the globe; and which is exemplified in the similarity of a corner of the island of Procida to the Rock of Burnt Stones. The island is situated to the west of the rock, and is about six leagues in circuit. The shore, being an accumulated mass of tufa, abounds with shrubs and plants. ‘This tufa on the side next Ischia, having been much corroded by the sea, affords a distinct view of its structure, which is in strata ;
CO ee se IN THER TWO SICILIES. 47 ula. whence we may infer that it has been the production of successive Auid dispositions. To sects the north-west of the island is a rock, on which we find pumices, pumiceous lava, and omer enamels, both pumiceous and pure, accompanied with feltspars, and the other con. the comitants with which they are found on the Rock of Burnt Stones; on which account it would be only loss cf time to recapitulate their description. I met with only one new lavas stone, which was a common granite, in which were distinctly discoverable its three con- wal: stituent parts : the feltspar in shining needles; a lightly livid, and slightly calcined quartz ; men; anda black mica, which did not shine. It could not therefore be doubted, that it had ye been exposed to the action of the fire. But as I found this granite loose on the shore, aver detached from the volcanic products I have before mentioned, I shall notice it no farther. ants From the lavas of the horn-sione base, found on this rock, we obtain in the furnace does @ very compact and hard enamel, which affords sparks with steel ; and from the lavas » weis the base of which is shoerl in the mass, as also from the pumice and the enamel, which P originate from the same stone, is poe a scorified enamel, so ebullient, that a great o the pee it boiled over the edges of the crucible, though it was only half full, This violent ranse usion, however, produced no sensible change in the feltspars. ticed I shall conclude this chapter with an observation relative to the enamels of the Rock re, as of Burnt Stones, and Procida, They are extremely friable; a slight stroke with a well hammer will break them into pieces; whereas the enamels of most other volcanos, as ter ts we shall see in their respective places, possess considerable hardness, and a much greater the than that of common glass. I imagine this defect may be caused by the sea-water which ’ the is mixed with them, and raised from the sea by the action of fire and aeri-form fluids. face Thus we know that those liquid vitreous substances which are congealed and consoli- a dated in water, are much more friable than when hardened in the air. I am confirmed cere in this opinion by observing, that a number cf cracks and fissures are to be found in these . first enamels, an appearance we likewise observe in glass which has been dropped into water 1. ond while in a state of fusion, It is to be remarked that these enamels, while they were cers fluid have received within them several extrancous bodies ; as picces of tufa and lava, o the sands and earths of various kinds, which are found within them more or less calcined. onl It is probable from the small distance between Procida and the Rock of Burnt Stones, pire that they once were joined, and have been separated, in the course of a long series of but, years, by the action of the sea. S less e far- » and auatter Its 7 h with ed in e are and lace of west ass of | been
48 SPALLANZANI’S TRAVELS
CHAPTER V. ISCHIA.
The Castle of Ischia founded on a rock of lava and tufa....Singular species of swallows, which make their nests at its tex, and on the higher eminences of the island.... Lava of the Arso des- cribed....Its pumices oviginate from the horn-stone.... The opinion of soe volcanic naturalists, that the lava of the Arso, which flowed in 1302, still smokes, ill foun Jed....Lavas and pumices scattered between the city of Ischia and the Arso....Conical mountain, called the Rotara, com- posed of lavas and pumices, is the only one in the island which contains enainels....The high mountain of St. Nicola. probably, at first, rose out of the sea.... Volcanic substances of that moun- tain....Some of those cubstances yield sulphate of alumine (alum)....Excursion round the shore of Ischia.... Volcanic productions found there....Ferruginous sand abundant on that island....Is found to be all crystallized....Inquiries concerning its origin.... No prismatic configuration in the lavas which fall into the sea.... The assertion of some modern writers, that tne lavas of the shores of Ischia are a nidus for the pholades, greatly to be doubted....The Stoves of Ischia, the only probable indication of a remaining internal conflagration....Cons‘derable diminution of this island...-Difference between the volcanic materials of Ischia and ‘hose of the other Phlegrean Fields....Singular property of the feltspars of the Ischian }:.vas, which melt in a glass furnace, whereas those of other lavas are almost always infusible by its heat.
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THE volcanic substances of which this island, eighteen miles in circuit, is internally composed, prove, beyond the possibility of doubt, that it owes its origin to fire. The obscure epochs of the eruptions of these substances have been fixed, by conjecture, by M. Niccola Andria, the learned professor royal in the university of Naples, in his in-
9 teresting work, entitled, Dec Acque Termali,* in which, before he treats of the warm
f springs of Ischia, he gives a detail of the natural history of the country, in which he
pieces displays equal learning and ingenuity. To this work 1 refer the curious reader, who Qo». (1 will find it extremely instructive.
I shall, however, according to the pian I originally proposed to myself, proceed to » describe the principa! productinns of this island which owe their origin to fire, adding such remarks as the subject may seem to render necessary. I shall begin therefore at the castle of the city of Ischia, which is built 01 a rock surrounded by the sea, and a
- little more than a quarter of a mile in circuit. Lava and tufa are the two component ‘ substances of this rock. The former is different in its appearance, according to the
different places in which it is found; but its qualities appeared to me to be substantially
ere : the same. its base is hornstone: it is compact, of a moderate hardness, an earthy ap- a. pearance ; of a black colour externally, but grayish within, Its dead lurid hue is di-
f versified by a few sparkling rhomboidal feltspars.
| The furnace produced from it a very compact enamel, of a mixed colour, between that of honey and dark blue, without any alteration in the feltspars.
| The tufa has no quality by which it is distinguished from the common.
. On examining the direction of the tufa and the lava, it was found to continue the
same in the neighbouring mountain, which is separated from the rock by a narrow chan-
nel of the sea: whence itis obvious to infer, that several currents have descended from
* On the waters of hot baths,
ws, Which Arso des- aturalists, d pumices tara, COM- The high at moun- the shore sland...1s tion in the the shores , the only on of this Phlegrean ss furnace,
internally re. The cture, by in his in- the warm which he der, who
roceed to -
re, adding erefore at ea, and a »mponent ing to the stantially arthy ap- hue is di-
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IN THE TWO SICILIES. 4?
the mountain and plunged into the water, thus forming the rock, which has been divided from the island by the action of the waves.
A number of black and white swallows* make their nests in different parts of this castle, and in »..¢ clefts of the rock. The steep and lofty rocks of the island, likewise, afford a secure retreat to these birds of passage.
Leaving the castle and the city of Ischia, and proceeding about a mile to the west, we meet with a torrent of lava, called the Arso (or Burnt Ground) which is the most re- cent of any in the island, since it flowed in 1302, and is described by Villani, in his History of Fiorence. It extended about half a mile in breadth, and about a mile and a half in length, and would have flowed farther, had it not met the sea, in which it was buried. The course of the torrrent appears interrupted by eminences and descents, and, at some distance, presents tc the eye the resemblance of an immense number of large heaps of mulberries confusedly thrown together. It has no visible crater, if by that term we understand, as is usual, a mouth more or less enlarged towards the edges, and contracted at the bottom; for the lava issued from a narrow cleft at the foot of Mount Tripeta. Though it is little less than five centuries since this lava flowed, a gloomy sterility reigns upon it ; it does not produce a single blade of grass, and only affords, in some places, a few arid and useless plants of the lichen, or liverwort. On the surface, and for a little depth, itis light and spongy, and easily crumbles; but deeper, it becomes dense and harder. The same is observable in many lavas, and is the natural effect of the laws cf gravity: the lighter parts of a liquid mass rising to the surface, and the hea- vier sinking to the ;
This lava is of the horn-stone base, and has an earthy ground.. Its colour is different in different places, and varies from that of iron toa reddish black. The feltspars incor. porated in it are extremely numerous, and, when attentively examined, in some speci- mens, may induce us to conclude that the fire which produced this torrent must have been extremely violent; since we find the feltspars more or less melted, though gene- rally, those included in lavas appear not to have undergone the least alteration. When, we take the lava of the Arso from some depth, in the middle of the current, we find this fusion of the feltspars extremely apparent. Some appear transformed into little globes, or cylinders; others have been only melted on one side, on which they have lost their crystallized form, though they have preserved it entire in other parts. In some cavities of the lava, where the fusion of the feltspars has been more considerable, we meet with singular appearances, which well deserve notice. Sometimes the melted feltspar hangs, as It were, in the air, attached only by some radiating threads of the lava itself, in the centre of which it hangs; while another, melting in the side of a cavity, takes the sha of a transparent concave veil. Even those that have not undergone fusion exhibit de- cisive signs of a strong calcination. They are extremely friable, and their shining changeable colour is in many places turned to a dead white. In consequence of this calcination, the crystals are often no longer found entire, but scattered here in small fragments in the body of the lava. Those in the lava on the sides of the current are less injured, and their crystallization is in quadrangular faces.
As the volcanic fire had reduced many of the feltspars in this lava to a state of fusion, I determined to try what effect I could produce on them in the furnace ; but though I kept them there two days, I could only obtain a simple calcination.
- Dolomieu, speaking of the island of Ischia, tells us that the eruption of the Arso, though we know it-continued two years, never produced any pumice, but only black
* Hirundo melba. Lin. VOL. V. : H
50 SPALLANZANI’S TAAVELS
| scorie.* It is true I could only find scoriaceous lava on the surface, and. solid lava in the internal parts, through the whole length of the course of the torrent, except at the | aperture whence it had flowed; where, amidst a great quaritity of fragments of lava, I | found several pieces of pumice so completely characterised, that there was no danger of . | confounding them with the light and porose scoria, which have been frequently by per- | sons of insufficient discernment, taken for pumices. These besides being dry and rough a to the touch, were fibrous, with long fibres, vitreous, extremely light, shining, and brit- tle; whcreas the texture of the scoriz and scoriaceous lava of the Arso is granulous, or so confused that no shadow of a fibre appears; nor have they much friability. In other respects, these pumices of the Arso agree in substance with the scoriz and lava of the same place; the feltspars in them are alike, and equally affected by the fire. This ob- servation proves therefore, that the horn-stone, by a violent fire may be changed into a true pumice, though this transmutation rarely happens.
The above-mentioned French naturalist likewise asserts, that the lava of the Arso still smokes in many places; and that the white fumes which rise from it are very visible in the morning when much dew has fallen.
This assertion, though it must appear somewhat extraordinary, would certainly merit belief, had M. Dolomieu himself been an eye-witness to the fact ; which had he been, he certainly would have told us. As however he only expresses himself in general terms, it is probable he relied on the information of others. The abbe Breislak and myself made our observations on the Arso, at the most proper time for discovering these fumes. We repaired thither at sun-rise, and passed there the greatest part of a morning in which there was no want of dew ; but our eyes sought this wonderful appearance in vain. Nor y, could we learn that it had been seen by any other persons; those at least of the inhabi- bi: tants of the vicinity whom we interrogated on the subject, and they were not few, nor , people likely to deceive us, all declared that they had never seen either smoke, vapour, ! or mist, arise from the Arso. However notwithstanding this, I will not take upon me absolutely to deny the fact. I will only say, that I find it difficult to overcome my iH doubts; nor am I convinced by the instances adduced by M. Dolomieu, of some lavas ny of Etna which have not yet ceased to smoke, though they were ejected in 1762; since the 7 pri elapsed in the latter case is only twenty-six years, but in the other four hundred and . eighty-six.
On my return to the city of Ischia, I met with three lavas rising from the earth like huge rocks. The base of all the three was the horn-stone, but they were distinguished from each other by certain exterior characters. ;
One of them was of a cinereous colour, of a coarse grain, but compact, dry, and rough to the touch. In its external appearance it was not unlike to :~me sand-stones, ° | The second was of a ground entirely earthy: its compactness, weight, and hardness were however greater than those of the first lava. at The third, in its recent fractures, was half vitreous; gave sparks with steel, but lan- ’ guidly;:.and was more fixed, heavy, and hard than the two others.
i ' All these three lavas had an argillaceous scent, and contained numerous feltspars so brilliant and perfect that they appeared to have entirely eluded the violence of the fire.
a eee
4 » A number of detached pumices accompanied these. lavas, which they resembled in yl their general qualities ; they contained feltspars and shoerls, but both reduced to a begin- i ning state of fusion.
* Catalogue Raisonnec des Produits de :'Etna.
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between Casamicciola and the city of Ischia. This mountain is of a conical shape, and composed of tufa, pumices, and enamels. It appears to have been produced by a thick and slimy eruption, and is divided into several strata, particularly distinguishable in the road called Via del Rotaro. Between these strata there is an immense quantity of pu- mices, differing in their size, colours, and density ; but similar in their texture, which in all is fibrous. They contain various feltspars, which manifest a beginning fusion. They do not form continued currents, as we observe in many of the pumices of Lipari, but are found in detached pieces; yet so disposed, that in many places they form beds or strata. It appears extremely probable, that the volcano, after an eruption of tufa, threw up a shower of pumices, which falling on the tufa produced a bed of stratum, upon which another eructation formed another tufaccous stratum, that was again covered with another shower of pumices ; and thus by alternate ejections of tufaceous and pu- miceous matters, a great part of the conical mountain was formed. ‘The extent of the pumices, in the direction of the Via del Rotaro, is more than a mile ; and they princi- pally abound in the more elevated places, where those most proper for the purposes for which these stones are used in Italy, may be collected in great abundance.
Intermixed with the pumices and tufa, we find many pieces of enamel, the thickness of which is from an inch to a foot and a half, and even two feet. ‘These were probably thrown out at the time when the above-mentioned mountain was formed. ‘They are of ‘a black colour, and yield to the strokes of a hammer much more than the enamels ot the Rock of Burnt Stones and Procida. Like them, they abound in feltspars, and pre- sent the usual rhomboidal figure. The Rotaro is the only place in Ischia which affords
" enamels.
It seems as if it might be considered as an invariable rule, that among the mountains of different elevation which have ‘iven birth to volcanic islands, that which rises above the rest, and is commonly placed ») the centre, was first produced by the fire ; and that those which surround it, and by their junction and extent form the body of the island, are the work of succeeding eruptions, whici have issued either from the crater of the
IN THE TWO SICILIES, 51 But no part of the island so abounds with pumices as the Rotaro, a mountain situated
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Pn primitive mountain, or from the lateral and lower craters, whence have been ejected that a gate of subaltern and successively lower mountains, by which the most elevated, h like which occupies the centre is surrounded. In this manner we perceive several of the ished Eolian isles to have been formed. Such also has been the origin of Ischia; where the mountain of St. Niccola, which in earlier times was called Epopeo, and which is in the ‘ough centre of the island, and higher than the rest, was no doubt the first that towered above the waves. The constituent substances of this mountain are of various kinds. I have drieas considered, with some attention, those on the side of Lacco. which are stones that in the. same manner as those of Solfatara, have undergone a de omposition probably to be at- ¢ lan. tributed to sulphureous acids, if from the resemblance of effects we may argue a simi- larity of cause. The rocks near the sea on the coast of Fasano are less decomposed ; nor td dey is it difficult to discover their nature, which is granitous ; the mica, feltspar, and quartz, fee being clearly discernible, with some greenish particles of steatites. The quartz and felt- ed in spars, though somewhat calcined, are tolerably hard ; and the mica which is black, has egin- not lost its native splendour. This rock, which does nct appear to have suffered fusion,
‘is whitish, and changed in such a manner that it will not resist a blow of the ham. mer.
Proceeding towards the summit of the Epopeo, we meet with decomposed lavas, partly of the horn-stone base, and partly of that of the petro-silex, in which however the argilla occupies no small part. ‘The lavas of this latter quality, in part not affected
H 2
52 SPALLANZANI’S TRAVELS
a
by the sulphureous acids, are of a black hue, of considerable compactness, give sparks freely with steel, and in their fractures, and sometimes externally, present a siliceous ap- pearance, Their odour is sensibly argillaceous. ‘These petrosiliceous lavas are not sim- ple, but contain within them some small flakes of feltspar and mice.
In the furnace they melt into a substance of the colour and lustre of pitch, in which. however the white feitspars appear, or rather are conspicuous.
These lavas are found to be variously decomposed by the acids, in the same manuer as is observable in those of Solfatara. In some places they are covered with a thin whitish crust, light, soft to the touch, which attaches to the tongue, and is extremely friable. In others this crust is sores inches deep, and in others it extends through the whole thick- ness of the lava. Sometimes we find it so softened that it has become pulverous ; and there is a great quantity of white dust on the brow of the mountain. ‘We may therefore conclude that the sulphureous acids have there been very abundant, and of long dura- tion; though now there is no perceivable sign of any such exhalations.
We know that formerly in Fschia the sulphate of alumine (alum) was extracted for commercial purposes ; and according to M. Andria, who has been before cited, the ma- nufacture of this salt was principally carried on at Catrico, a place situated above Lacco, on the higher eminences of the Epopeo. He informs us however, that he was not able, after the most careful and minute research, to discover any remaining vestige of sulphate of alumine. I will candidly state what I myself heaved,
I collected a number of specimens of the different lavas of Catrico and the environs. They are generally compact, very white, and homogeneous to the eye; but they differ from each other by the following exterior characters. Some are moderately heavy and hard ; in their recent fractures, and frequently without, they are smooth; and in the centre of some we finda small nucleus of blackish lava, but little decomposed. Others are very light, may be scratched by the nail, are rough and somewhat pulverous in their factures, and scarcely ever contain within them any residue not senor pees In short, the former lavas have undergone less change by the sulphureous acids than the latter. When I first examined on the spot the fragments of these two lavas, I could not per. ceive by the taste any s mptom of the sulphate of alumine ; but when I had con. veyed my specimens to Pavia, together with other volcanic substances, and placed them in my cabinet, on large tables, after some months I observed the following ap- pearances :
In the lavas of Catrico and its vicinity, which had been less affected by the acids, I could discover ne trace of alum; but in the other lavas of the same situation, which had been more changed by the said acids, I perceived the sweetish and astringent taste of that salt; and could discover a whitish thin coat of the same, which entirely in- crusted them.
At the end of six months the thickness of this coat was a quarter of a line; after which, I did not perceive it to encrease in thickness. I made new fractures in these lavas, and continually discovered new coats of the sulphate of alumine ; and at the time I now write, which is twenty-seven months since I brought the specimens of lave from Ischia, they still retain a thin saline crust. I have also satisfactorily ascertained the true nature of this sulphate of alumine, by the ordinary chemical proofs.
As to the second species of lava, it never at any time exhibited any sign of the pre- sence of this sulphate; nor have I been able to obtain it by calcination, and a method similar to that which is employed in the territory of Civita Vecchia for extracting alum from such argillaceous stones.
laced > Ap-
LO <A ee a a et Ye
IN THE TWO SICILIES. 53
"These observations however sufficiently prove, that this valuable salt might still be obtained at Ischia; nor should it excite surprise that, when on the spot I could not dis- cover it by the taste ; since the humidity of the night, the dew, and still more the rains, had dissipated it as fast as it efloresced. As the species of decomposed lava in which I discovered it, is found in very large quantities on the Epopeo, this branch of com- merce, which has been so long neglected in Ischia, might doubtless be revived with very great advantage.
esides the places I have mentioned, I examined this island in many others, without discovering any novelty worthy of remark ; but I could not entirely satisfy 5 feed with such excursions. When I first formed the design of attentively examining Ischia and the Eolian isles, I resolved not only to make my researches in their interior parts, but to coast their shores in a boat, landing at such places as appeared the most suitable to my inquiries. In this manner I met with many volcanic bodies, which I should have sought in vain within the island ; either because they do not exist there, or because they are rendered inaccessible by the rocks and pree’mices with which they are surrounded, or which they themselves form. The coasts of the volcanic isles are also clothed with lavas, which run out into the sea, and which in some places, by tracing them upwards, discover the crater or mouth from which they have issued. Lastly, by coasting the shores of the islands, we may be enabled to determine whether the prismatic laviis owe their origin to the sea; many writers of repute having asserted that the regularity of their form arises from the sudden congelation that takes place on their precipitating into the sea-water, which causes them to take the shape of regular prismatic columns; a con- figuration which they affirm is only found in places adjoining to the sea.
For these reasons I determined, after having examined the higher parts of the island, to proceed to consider the lower; and took my departure from Lacco by water, coasting
‘the island on the left. The first mountain which presented itself was the Vico, partly
formed of tufa, and partly of two currents of lava, which descend into the sea. The colour of the first, which is of a horn-stone base, is between the gray and iron colour : itis of an unequal grain, earthy, and moderately hard; and abounds in feltspars, some in thin plates, others in prisms, and both conspicuous for their brilliancy.
The other lava, which is of the same base, and contains similar feltspars, is less com- pact, more earthy, and consequently less hard: its colour is partly cinereous, and part- ly gray. These two lavas, in their descent, have raised themselves into little mounts, and are of a considerable thickness.
Farther on is Monte Zaro, formed towards the sea by a river of lava extending a mile in length, and nearly two in breadth. It appears to have been generated by several successive eruptions, which have consolidated one after the other. The base of this lava is horn-stone, and it contains nzica and feltspars. It is various in its colour, being in some parts of the current of a more or less'reddish blue, in others cinereous, and in others white. The mica, which is black, and especially conspicuous in the white pieces, though it has not undergone fusion, has lost its lustre, and acquired a much greater de of friability than it naturally has. The same has not happened to the feltspars, which are as well preserved as if they had never been exposed to the fire. They give sparks plentifully with steel, have a beauteous changeable lustre, are of a vitreous semi-transparent whiteness, and being broken, are detached with difficulty. ‘This spe- cies of lava so abounds with them, that they occupy the full half of its volume. .The greater part are prisms.
__ Another lava makes a part of the same current of Monte Zaro. This, though it is likewise of a horn-stone base, differs from the former by being one-third less heavy, and
i
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54 SPALLANZANI’S TRAVELS
of an earthy appearance ; whereas that of the other is somewhat vitreous. Its colour in the more internal parts is reddish; but in the external an ochreous yellow. On the surface especially it is manifestly decomposed ; for it is become so soft that it may be scraped with a knife. But the cause which has produced this superficial decomposition in the lava has not injured the feltspars, which are extremely perfect, and in this lava may be easily extracted to examine their figure, which is hexagona! with rhomboidal faces. Some of them are half an inch in length, though others are not more than a line.
‘The bottom of Monte Zaro, which is washed by the sea, is covered with a vitreous sind ; which viewed with a lens, appears to consist of a number of particles of feltspars, which by liquefaction have had their angles blunted, and been reduced to a roundish figure. They belong to the feltspars of the last mentioned lava,
From the termination of Monte Zaro to the beginning of Monte Imperatore is a long and ample tract, almost entirely tufaceous, scattered over with rapillo, as the Neapolitans call it; or as 2 naturalist would say, with fragments of pumice.
The side of Monte Imperatore which over-hangs the sea, derives its origin from a very singular species of lava.’ I have already spoken of the abundance of feltspars in the lava of Monte Zara; but in this they are found so prodigiously numerous, that at first view they appear to constitute the entire substance. It is necessary to break it, and con- sider the pieces attentively, to perceive that it has a base, which is of a yellowish earthy horn-stone, easily friable, to very small quantities of which the feltspars are feebly attach- ed. Their crystallization is in rhomboidal faces of various sizes, from a line to three quarters of an inch. To this little earthy base are likewise attached various small scales of black hexzdrous mica.
The same Monte [mperatore presents us on the side of the sea with large quantities of another lava; which, excepting a very few particles of yellow mica, and some still fewer microscopic feltspars, may be considered as simple. This likewise has for its base the horn-stone. ‘The lava appears to have issued from the mouth of the volcano at different times, as we find currents which have flowed over currents, intermixed in a strange and confused manner.
Leaving the Monte Imperatore, we next arrive at the Calle di Panza ; a place on the shore from which rises a very high and large rock of lava, interrupted by some protuber- ances, that attract the eye ata distance and invite observation, which they certainly me- rit, as they consist of beautiful groups of numerous rough rhomboidal feltspars, some two inches in length. They are of a yellowish white, transparent in a slight degree, of a vitreous appearance, a changing aspect, a foliating texture, and manifest their hardness by the quantity of sparks they give with steel. Many hundreds of them grouped toge- ther, furm roundish masses of half a foot, a foot, and two feet in thickness, which at their lower extremity are set in the lava. Though, as has been said, they are very hard ; yet by the means of certain fissures they contain, they may easily be divided into small pieces, either of the parallelopipedon or rhomboidal form. Whence it appears that they have been injured by some external agent, but which seems to have had no relation to sulphureous acid vapours, as we do not perceive the smallest indication of these, cither in the feltspars or in the lava which contains them. ‘This agent however, whatever it may have been, has produced a considerable effect on the lava, which is corroded in every part; and it is in consequence of its being so deeply corroded, that the groups of feltspars have been left uncovered, so that they may easily with an iron point be extracted entire.
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IN THE TWO SICILIES. 55
This fact appeared to me the more deserving of remark, as in all my former volcanic researches I had never met with any similar; nor indeed have I since ; the feltspars of other lavas being never grouped, or forming a kind of tumours, but scattered and distri- buted within them in equal quantities. But in